
           LX - Linear eXecutable Module Format Description

                            June 3, 1992



   Figure 1. 32-bit Linear EXE File Layout

       00h +------------------+  <--+
           | DOS 2 Compatible |     |
           |    EXE Header    |     |
       1Ch +------------------+     |
           |      unused      |     |
           +------------------+     |
       24h |  OEM Identifier  |     |
       26h |  OEM Info        |     |
           |                  |     |-- DOS 2.0 Section
       3Ch |  Offset to       |     |   (Discarded)
           |  Linear EXE      |     |
           |  Header          |     |
       40h +------------------+     |
           |   DOS 2.0 Stub   |     |
           |   Program &      |     |
           |   Reloc. Table   |     |
           +------------------+  <--+
           |                  |
       xxh +------------------+  <--+
           |    Executable    |     |
           |       Info       |     |
           +------------------+     |
           |      Module      |     |
           |       Info       |     |
           +------------------+     |-- Linear Executable
           |  Loader Section  |     |   Module Header
           |       Info       |     |   (Resident)
           +------------------+     |
           |   Table Offset   |     |
           |       Info       |     |
           +------------------+  <--+
           |   Object Table   |     |
           +------------------+     |
           | Object Page Table|     |
           +------------------+     |
           |  Resource Table  |     |
           +------------------+     |
           |  Resident Name   |     |
           |      Table       |     |
           +------------------+     |-- Loader Section
           |   Entry Table    |     |   (Resident)
           +------------------+     |
           |   Module Format  |     |
           | Directives Table |     |
           |    (Optional)    |     |
           +------------------+     |
           |     Resident     |     |
           | Directives Data  |     |
           |    (Optional)    |     |
           |                  |     |
           |  (Verify Record) |     |
           +------------------+     |
           |     Per-Page     |     |
           |     Checksum     |     |
           +------------------+  <--+
           | Fixup Page Table |     |
           +------------------+     |
           |   Fixup Record   |     |
           |       Table      |     |
           +------------------+     |-- Fixup Section
           |   Import Module  |     |   (Optionally Resident)
           |    Name Table    |     |
           +------------------+     |
           | Import Procedure |     |
           |    Name Table    |     |
           +------------------+  <--+
           |   Preload Pages  |     |
           +------------------+     |
           |    Demand Load   |     |
           |       Pages      |     |
           +------------------+     |
           |  Iterated Pages  |     |
           +------------------+     |
           |   Non-Resident   |     |-- (Non-Resident)
           |    Name Table    |     |
           +------------------+     |
           |   Non-Resident   |     |
           | Directives Data  |     |
           |    (Optional)    |     |
           |                  |     |
           |  (To be Defined) |     |
           +------------------+  <--+
           |    Debug Info    |     |-- (Not used by Loader)
           +------------------+  <--+



 Figure 2. 32-bit Linear EXE Header

           +-----+-----+-----+-----+-----+-----+-----+-----+
       00h | "L"   "X" |B-ORD|W-ORD|     FORMAT LEVEL      |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       08h | CPU TYPE  |  OS TYPE  |    MODULE VERSION     |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       10h |     MODULE FLAGS      |   MODULE # OF PAGES   |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       18h |     EIP OBJECT #      |          EIP          |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       20h |     ESP OBJECT #      |          ESP          |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       28h |       PAGE SIZE       |   PAGE OFFSET SHIFT   |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       30h |  FIXUP SECTION SIZE   | FIXUP SECTION CHECKSUM|
           +-----+-----+-----+-----+-----+-----+-----+-----+
       38h |  LOADER SECTION SIZE  |LOADER SECTION CHECKSUM|
           +-----+-----+-----+-----+-----+-----+-----+-----+
       40h |    OBJECT TABLE OFF   |  # OBJECTS IN MODULE  |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       48h | OBJECT PAGE TABLE OFF | OBJECT ITER PAGES OFF |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       50h | RESOURCE TABLE OFFSET |#RESOURCE TABLE ENTRIES|
           +-----+-----+-----+-----+-----+-----+-----+-----+
       58h | RESIDENT NAME TBL OFF |   ENTRY TABLE OFFSET  |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       60h | MODULE DIRECTIVES OFF | # MODULE DIRECTIVES   |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       68h | FIXUP PAGE TABLE OFF  |FIXUP RECORD TABLE OFF |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       70h | IMPORT MODULE TBL OFF | # IMPORT MOD ENTRIES  |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       78h |  IMPORT PROC TBL OFF  | PER-PAGE CHECKSUM OFF |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       80h |   DATA PAGES OFFSET   |    #PRELOAD PAGES     |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       88h | NON-RES NAME TBL OFF  | NON-RES NAME TBL LEN  |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       90h | NON-RES NAME TBL CKSM |   AUTO DS OBJECT #    |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       98h |    DEBUG INFO OFF     |    DEBUG INFO LEN     |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       A0h |   #INSTANCE PRELOAD   |   #INSTANCE DEMAND    |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       A8h |       HEAPSIZE        |
           +-----+-----+-----+-----+

 Note: The OBJECT ITER PAGES OFF must either be 0 or set to the
 same value as DATA PAGES OFFSET in OS/2 2.0. Ie., iterated pages are
 required to be in the same section of the file as regular pages.

 Note: Table offsets  in the Linear  EXE Header may be set to
 zero  to indicate that the table does not  exist in the  EXE
 file and it's size is zero.

     "L" "X" = DW  Signature word.
         The signature word is used by the loader to identify
         the EXE file as  a valid  32-bit  Linear  Executable
         Module  Format.  "L" is low order byte. "X"  is high
         order byte.

     B-ORD = DB  Byte Ordering.
         This byte specifies the byte ordering for the linear
         EXE format.  The values are:

             00H - Little Endian Byte Ordering.
             01H - Big Endian Byte Ordering.

     W-ORD = DB  Word Ordering.
         This byte specifies the Word ordering for the linear
         EXE format.  The values are:

             00H - Little Endian Word Ordering.
             01H - Big Endian Word Ordering.

     Format Level = DD  Linear EXE Format Level.
         The  Linear EXE Format Level is set  to  0  for  the
         initial version  of  the 32-bit linear  EXE  format.
         Each  incompatible  change to the  linear EXE format
         must increment this value.  This  allows the  system
         to recognized future EXE file versions  so  that  an
         appropriate  error message  may  be displayed  if an
         attempt is made to load them.

     CPU Type = DW  Module CPU Type.
         This  field specifies the type  of  CPU required  by
         this module to run.  The values are:

             01H  -  80286  or  upwardly  compatible  CPU  is
             required to execute this module.
             02H  -  80386  or  upwardly  compatible  CPU  is
             required to execute this module.
             03H  -  80486  or  upwardly  compatible  CPU  is
             required to execute this module.

     OS Type = DW  Module OS Type.
         This field specifies the type  of  Operating  system
         required to run  this module.  The currently defined
         values are:

             00H - Unknown (any "new-format" OS)
             01H - OS/2 (default)
             02H - Windows
             03H - DOS 4.x
             04H - Windows 386

     MODULE VERSION = DD  Version of the linear EXE module.
         This is useful for differentiating between revisions
         of dynamic linked modules.  This  value is specified
         at link time by the user.

     MODULE FLAGS = DD  Flag bits for the module.
         The module flag bits have the following definitions.

             00000001h = Reserved for system use.
             00000002h = Reserved for system use.
             00000004h = Per-Process Library Initialization.
                 The setting  of this  bit  requires the  EIP
                 Object  #  and  EIP  fields  to  have  valid
                 values.  If the EIP Object # and EIP  fields
                 are  valid  and this  bit is  NOT  set, then
                 Global Library  Initialization  is  assumed.
                 Setting this bit for an EXE file is invalid.

             00000008h = Reserved for system use.
             00000010h = Internal fixups for the  module have
             been applied.
                 The  setting   of  this  bit  in  a   Linear
                 Executable Module indicates that each object
                 of  the module  has a preferred load address
                 specified  in  the Object  Table  Reloc Base
                 Addr.  If the module's  objects  can  not be
                 loaded at  these  preferred  addresses, then
                 the   relocation  records  that  have   been
                 retained in the file data will be applied.

             00000020h = External fixups for  the module have
             been applied.
             00000040h = Reserved for system use.
             00000080h = Reserved for system use.
             00000100h = Incompatible with PM windowing.
             00000200h = Compatible with PM windowing.
             00000300h = Uses PM windowing API.
             00000400h = Reserved for system use.
             00000800h = Reserved for system use.
             00001000h = Reserved for system use.
             00002000h = Module is not loadable.
                 When  the 'Module is  not loadable' flag  is
                 set, it indicates that  either  errors  were
                 detected at link  time or that the module is
                 being  incrementally  linked  and  therefore
                 can't be loaded.

             00004000h = Reserved for system use.
             00038000h = Module type mask.
             00000000h = Program module.
                 A module  can not  contain  dynamic links to
                 other modules that have the 'program module'
                 type.

             00008000h = Library module.
             00018000h = Protected Memory Library module.
             00020000h = Physical Device Driver module.
             00028000h = Virtual Device Driver module.
             40000000h = Per-process Library Termination.
                 The  setting of this bit  requires  the  EIP
                 Object  #  and  EIP  fields  to  have  valid
                 values.  If the EIP Object  # and EIP fields
                 are  valid  and  this bit  is NOT  set, then
                 Global  Library   Termination   is  assumed.
                 Setting this bit for an EXE file is invalid.

     MODULE # PAGES = DD  Number of pages in module.

         This field specifies the number of  pages physically
         contained in  this module.  In  other  words,  pages
         containing  either enumerated or  iterated data,  or
         zero-fill pages  that have relocations,  not invalid
         or zero-fill  pages implied by  the  Virtual Size in
         the Object  Table being  larger  than  the number of
         pages actually in  the linear EXE file.  These pages
         are  contained in the  'preload pages', 'demand load
         pages'  and  'iterated  data pages' sections of  the
         linear EXE module.  This  is  used  to determine the
         size  of the page information tables  in  the linear
         EXE module.

     EIP OBJECT #  = DD The Object number to which  the Entry
     Address is relative.
         This specifies the object to which the Entry Address
         is  relative.  This must be a  nonzero  value  for a
         program module to be correctly loaded.  A zero value
         for a library module indicates that no library entry
         routine exists.  If  this  value  is zero, then both
         the  Per-process Library Initialization bit and  the
         Per-process Library Termination bit must be clear in
         the module flags,  or  else the loader will fail  to
         load   the  module.  Further,  if  the   Per-process
         Library Termination  bit is set, then the  object to
         which  this field  refers  must  be a 32-bit  object
         (i.e., the Big/Default bit must be set in the object
         flags; see below).

     EIP = DD  Entry Address of module.
         The  Entry  Address  is  the  starting  address  for
         program modules and  the  library initialization and
         Library termination address for library modules.

     ESP OBJECT # = DD The Object number to  which the ESP is
     relative.
         This  specifies the object to which the starting ESP
         is relative.  This  must be  a  nonzero  value for a
         program  module to be correctly  loaded.  This field
         is ignored for a library module.

     ESP = DD  Starting stack address of module.
         The  ESP defines the starting stack  pointer address
         for program modules.  A zero  value  in  this  field
         indicates   that   the  stack  pointer   is  to   be
         initialized  to the  highest  address/offset in  the
         object.  This field is ignored for a library module.

     PAGE SIZE = DD  The size of one page for this system.
         This  field  specifies  the  page size  used  by the
         linear EXE  format and the  system.  For the initial
         version of this linear  EXE format the page  size is
         4Kbytes.  (The 4K page size  is specified by a value
         of 4096 in this field.)

     PAGE OFFSET  SHIFT = DD  The shift left  bits  for  page
     offsets.
         This  field  gives the number  of bit  positions  to
         shift left when interpreting  the  Object Page Table
         entries' page  offset  field.  This  determines  the
         alignment  of the page information in the file.  For
         example, a value of  4 in this field would align all
         pages in the  Data Pages and Iterated Pages sections
         on 16  byte  (paragraph)  boundaries.  A Page Offset
         Shift of 9 would align all pages on a 512 byte (disk
         sector) basis.  The default  value for this field is
         12 (decimal), which give a 4096 byte alignment.  All
         other offsets are byte aligned.

     FIXUP  SECTION  SIZE  =  DD  Total  size  of  the  fixup
     information in bytes.
         This includes the following 4 tables:

             - Fixup Page Table
             - Fixup Record Table
             - Import Module name Table
             - Import Procedure Name Table

     FIXUP  SECTION  CHECKSUM   =   DD   Checksum  for  fixup
     information.
         This is a cryptographic checksum covering all of the
         fixup  information.  The  checksum   for  the  fixup
         information  is kept separate because the fixup data
         is  not  always loaded into  main  memory  with  the
         'loader  section'.  If  the  checksum feature is not
         implemented, then the  linker will set  these fields
         to zero.

     LOADER  SECTION  SIZE  =  DD  Size  of  memory  resident
     tables.
         This  is  the  total  size  in bytes of  the  tables
         required to be memory resident for the module, while
         the module is in use.  This total size  includes all
         tables from the Object  Table down to  and including
         the Per-Page Checksum Table.

     LOADER  SECTION  CHECKSUM  =  DD  Checksum   for  loader
     section.
         This is a cryptographic checksum covering all of the
         loader section information.  If the checksum feature
         is not implemented,  then the linker  will set these
         fields to zero.

     OBJECT TABLE OFF = DD  Object Table offset.
         This offset  is  relative  to  the  beginning of the
         linear EXE header.

     # OBJECTS IN MODULE = DD  Object Table Count.
         This defines the number of entries in Object Table.

     OBJECT PAGE TABLE OFFSET = DD  Object Page Table offset
         This offset is  relative  to  the beginning  of  the
         linear EXE header.

     OBJECT  ITER  PAGES  OFF  =  DD  Object  Iterated  Pages
     offset.
         This offset is relative to the beginning of  the EXE
         file.

     RESOURCE TABLE OFF = DD  Resource Table offset.
         This offset is relative  to  the  beginning  of  the
         linear EXE header.

     # RESOURCE  TABLE  ENTRIES  = DD  Number  of entries  in
     Resource Table.

     RESIDENT NAME TBL OFF = DD  Resident Name Table offset.
         This offset is  relative  to  the  beginning  of the
         linear EXE header.

     ENTRY TBL OFF = DD  Entry Table offset.
         This  offset  is  relative  to the beginning of  the
         linear EXE header.

     MODULE DIRECTIVES  OFF  =  DD  Module  Format Directives
     Table offset.
         This  offset  is  relative  to  the beginning of the
         linear EXE header.

     #  MODULE  DIRECTIVES  =  DD  Number  of  Module  Format
     Directives in the Table.
         This field specifies the number  of  entries in  the
         Module Format Directives Table.

     FIXUP PAGE TABLE OFF = DD  Fixup Page Table offset.
         This  offset  is  relative to the  beginning of  the
         linear EXE header.

     FIXUP RECORD TABLE OFF = DD  Fixup Record Table Offset
         This  offset is relative to  the  beginning  of  the
         linear EXE header.

     IMPORT  MODULE  TBL  OFF = DD  Import  Module Name Table
     offset.
         This  offset is relative  to  the  beginning of  the
         linear EXE header.

     # IMPORT MOD ENTRIES = DD  The  number of entries in the
     Import Module Name Table.

     IMPORT PROC TBL OFF  =  DD  Import Procedure  Name Table
     offset.
         This offset  is relative  to  the  beginning of  the
         linear EXE header.

     PER-PAGE CHECKSUM  OFF  =  DD  Per-Page  Checksum  Table
     offset.
         This  offset is  relative  to  the beginning of  the
         linear EXE header.

     DATA PAGES OFFSET = DD   Data Pages Offset.
         This offset is  relative to the beginning of the EXE
         file.

     # PRELOAD PAGES = DD  Number  of  Preload pages for this
     module. Note that OS/2 2.0 does not respect the preload
     of pages as specified in the executable file for performance
     reasons.

     NON-RES NAME  TBL  OFF  =  DD  Non-Resident  Name  Table
     offset.
         This offset is relative to the beginning of  the EXE
         file.

     NON-RES  NAME  TBL  LEN = DD  Number  of  bytes  in  the
     Non-resident name table.

     NON-RES  NAME TBL CKSM  =  DD  Non-Resident  Name  Table
     Checksum.
         This is a cryptographic checksum of the Non-Resident
         Name Table.

     AUTO  DS OBJECT  #  =  DD  The Auto Data  Segment Object
     number.
         This is the object number for  the Auto Data Segment
         used by 16-bit modules.  This field is supported for
         16-bit compatibility only and is not used by  32-bit
         modules.

     DEBUG INFO OFF = DD  Debug Information offset.
         This offset  is relative  to  the  beginning  of the
         linear EXE header.

     DEBUG INFO LEN = DD  Debug Information length.
         The length of the debug information in bytes.

      #  INSTANCE  PRELOAD  = DD Instance  pages  in  preload
     section.
         The  number  of instance  data pages  found  in  the
         preload section.

      #  INSTANCE  DEMAND  =  DD  Instance  pages  in  demand
     section.
         The  number  of instance  data pages  found  in  the
         demand section.

      HEAPSIZE = DD Heap size added to the Auto DS Object.
         The heap size is the  number  of  bytes added to the
         Auto  Data  Segment  by the loader.  This  field  is
         supported for  16-bit compatibility only and is  not
         used by 32-bit modules.





     Program (EXE) startup registers and Library entry registers


     Program startup registers are defined as follows.

         EIP = Starting program entry address.

         ESP = Top of stack address.

         CS = Code selector for base of linear address space.

         DS =  ES  = SS = Data  selector  for  base of linear
         address space.

         FS =  Data selector  of  base of Thread  Information
         Block (TIB).

         GS = 0.

         EAX = EBX = 0.

         ECX = EDX = 0.

         ESI = EDI = 0.

         EBP = 0.

         [ESP+0] =  Return  address to  routine  which  calls
         DosExit(1,EAX).

         [ESP+4] = Module handle for program module.

         [ESP+8] = Reserved.

         [ESP+12] = Environment data object address.

         [ESP+16]   =   Command  line   linear   address   in
         environment data object.


     Library initialization registers are defined as follows.

         EIP = Library entry address.

         ESP = User program stack.

         CS = Code selector for base of linear address space.

         DS  = ES = SS = Data  selector  for  base  of linear
         address space.

         Note that a  32-bit Protected Memory Library  module
         will be  given  a  GDT  selector in  the  DS  and ES
         registers (PROTDS)  that  addresses the  full linear
         address  space  available  to  a  application.  This
         selector  should  be  saved  by  the  initialization
         routine.  Non-Protected  Memory Library modules will
         receive a selector (FLATDS) that  addresses the same
         amount of linear  address  space as an application's
         .EXE can.

         FS  = Data selector  of base  of  Thread Information
         Block (TIB).

         GS = 0.

         EAX = EBX = 0.

         ECX = EDX = 0.

         ESI = EDI = 0.

         EBP = 0.

         [ESP+0] = Return address to system, (EAX)  =  return
         code.

         [ESP+4] = Module handle for library module.

         [ESP+8] = 0 (Initialization)

     Note that a  32-bit  library may specify  that its entry
     address is  in  a 16-bit code object.  In this case, the
     entry registers are the same  as for  entry to a library
     using the Segmented  EXE format.  These  are  documented
     elsewhere.  This  means  that  a  16-bit  library may be
     relinked to take advantage of the benefits of the Linear
     EXE format (notably, efficient paging).


     Library termination registers are defined as follows.

         EIP = Library entry address.

         ESP = User program stack.

         CS = Code selector for base of linear address space.

         DS  =  ES  = SS  = Data  selector for base of linear
         address space.

         FS  =  Data  selector of base of  Thread Information
         Block (TIB).

         GS = 0.

         EAX = EBX = 0.

         ECX = EDX = 0.

         ESI = EDI = 0.

         EBP = 0.

         [ESP+0] = Return address to system.

         [ESP+4] = Module handle for library module.

         [ESP+8] = 1 (Termination)

     Note  that  Library  termination  is  not  allowed   for
     libraries with 16-bit entries.





     Object Table


 The number of entries in the Object Table  is given by the #
 Objects in Module  field  in the linear EXE header.  Entries
 in the Object Table are numbered starting from one.

 Each Object Table entry has the following format:

           +-----+-----+-----+-----+-----+-----+-----+-----+
       00h |     VIRTUAL SIZE      |    RELOC BASE ADDR    |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       08h |     OBJECT FLAGS      |    PAGE TABLE INDEX   |
           +-----+-----+-----+-----+-----+-----+-----+-----+
       10h |  # PAGE TABLE ENTRIES |       RESERVED        |
           +-----+-----+-----+-----+-----+-----+-----+-----+

     VIRTUAL SIZE = DD  Virtual memory size.
         This  is  the  size  of  the  object  that  will  be
         allocated  when the object is loaded.  The  object's
         virtual  size (rounded  up to  the page  size value)
         must be  greater than or equal to the total  size of
         the  pages  in the  EXE  file  for the object.  This
         memory size must also be large enough to contain all
         of the iterated data and uninitialized  data in  the
         EXE file.

     RELOC BASE ADDR = DD Relocation Base Address.
         The relocation base  address the object is currently
         relocated to.  If the internal relocation fixups for
         the  module have been  removed, this is  the address
         the object will be allocated at by the loader.

     OBJECT FLAGS = DW  Flag bits for the object.
         The object flag bits have the following definitions.

             0001h = Readable Object.
             0002h = Writable Object.
             0004h = Executable Object.
                 The readable,  writable and executable flags
                 provide    support    for    all    possible
                 protections.  In systems where  all of these
                 protections are not  supported,  the  loader
                 will   be   responsible   for   making   the
                 appropriate protection match for the system.

             0008h = Resource Object.
             0010h = Discardable Object.
             0020h = Object is Shared.
             0040h = Object has Preload Pages.
             0080h = Object has Invalid Pages.
             0100h = Object has Zero Filled Pages.
             0200h = Object is Resident (valid for VDDs, PDDs
             only).
             0300h = Object is Resident  &  Contiguous (VDDs,
             PDDs only).
             0400h  =  Object is  Resident  & 'long-lockable'
             (VDDs, PDDs only).
             0800h = Reserved for system use.
             1000h = 16:16 Alias Required (80x86 Specific).
             2000h   =   Big/Default   Bit   Setting   (80x86
             Specific).
                 The 'big/default'  bit , for data  segments,
                 controls the setting of the Big  bit  in the
                 segment descriptor.  (The Big bit, or B-bit,
                 determines whether ESP or SP is used  as the
                 stack pointer.)  For code segments, this bit
                 controls the setting of the  Default  bit in
                 the segment descriptor.  (The  Default  bit,
                 or  D-bit, determines  whether  the  default
                 word  size  is 32-bits or 16-bits.  It  also
                 affects   the    interpretation    of    the
                 instruction stream.)

             4000h =  Object is  conforming  for  code (80x86
             Specific).
             8000h  =  Object  I/O  privilege   level  (80x86
             Specific).
                 Only used for 16:16 Alias Objects.

     PAGE TABLE INDEX = DD  Object Page Table Index.
         This specifies the number of  the first  object page
         table  entry for this object.  The object page table
         specifies where in the EXE file a page  can be found
         for   a   given   object   and   specifies  per-page
         attributes.

         The object table entries are ordered by logical page
         in the  object  table.  In  other  words  the object
         table entries  are sorted based  on  the object page
         table index value.

     #  PAGE TABLE ENTRIES  =  DD  #  of  object  page  table
     entries for this object.
         Any logical pages at the  end  of an  object that do
         not  have  an   entry   in  the  object  page  table
         associated  with them are handled as zero  filled or
         invalid pages by the loader.

         When the last  logical pages  of an  object  are not
         specified with an object page table entry,  they are
         treated as either zero filled pages or invalid pages
         based on the last entry in the object page table for
         that object.  If  the last entry was  neither a zero
         filled  or invalid  page, then the additional  pages
         are treated as zero filled pages.

     RESERVED = DD  Reserved for future use.  Must  be set to
     zero.



     Object Page Table


 The  Object  page table provides information about a logical
 page in  an object.  A  logical  page  may be  an enumerated
 page, a pseudo page or an iterated  page.  The  structure of
 the  object page table in conjunction with the  structure of
 the  object table allows for efficient access of a page when
 a page fault occurs, while  still allowing the physical page
 data to be located  in the preload page, demand load page or
 iterated data  page sections in the linear  EXE  module. The
 logical page entries  in the Object Page Table  are numbered
 starting from one.  The Object Page Table is parallel to the
 Fixup  Page Table  as  they are both indexed by the  logical
 page number.

 Each Object Page Table entry has the following format:

          63                     32 31       16 15         0
           +-----+-----+-----+-----+-----+-----+-----+-----+
       00h |    PAGE DATA OFFSET   | DATA SIZE |   FLAGS   |
           +-----+-----+-----+-----+-----+-----+-----+-----+

     PAGE DATA OFFSET = DD  Offset  to  the page  data in the
     EXE file.
         This field, when bit shifted left by the PAGE OFFSET
         SHIFT from the  module header, specifies  the offset
         from  the beginning of  the Preload Page section  of
         the  physical  page  data  in   the  EXE  file  that
         corresponds to this logical  page  entry.  The  page
         data  may  reside in the  Preload Pages, Demand Load
         Pages or the Iterated Data Pages sections.

         If  the  FLAGS  field  specifies  that  this  is   a
         zero-Filled page  then the  PAGE DATA  OFFSET  field
         will contain a 0.

         If the logical page is specified as an iterated data
         page,  as  indicated  by the FLAGS field, then  this
         field specifies the  offset into the  Iterated  Data
         Pages section.

         The logical page number  (Object Page  Table index),
         is  used  to index  the Fixup Page Table to find any
         fixups associated with the logical page.


     DATA SIZE = DW  Number of bytes of data for this page.
         This field specifies the actual number of bytes that
         represent the page in  the  file.  If  the PAGE SIZE
         field  from the  module header is greater  than  the
         value of this  field and the FLAGS field indicates a
         Legal Physical  Page,  the remaining bytes are to be
         filled with zeros.  If  the FLAGS field indicates an
         Iterated  Data Page,  the iterated data records will
         completely fill out the remainder.


     FLAGS =  DW  Attributes  specifying  characteristics  of
     this logical page.
         The bit definitions for this word field follow,

             00h = Legal Physical Page  in the module (Offset
             from Preload Page Section).
             01h  = Iterated Data Page (Offset from  Iterated
             Data Pages Section).
             02h = Invalid Page (zero).
             03h = Zero Filled Page (zero).
             04h = Range of Pages.




     Resource Table


 The resource table is  an array of  resource  table entries.
 Each resource  table entry  contains  a type ID and name ID.
 These entries  are used to locate resource objects contained
 in the Object table.  The number  of entries in the resource
 table is defined by the  Resource Table Count located in the
 linear EXE  header.  More than one resource may be contained
 within  a  single  object.  Resource table entries are in  a
 sorted  order,  (ascending,  by Resource Name ID  within the
 Resource  Type  ID).  This  allows  the  DosGetResource  API
 function to use a binary search when looking  up  a resource
 in  a 32-bit module instead of the linear  search being used
 in the current 16-bit module.

 Each resource entry has the following format:

           +-----+-----+-----+-----+
       00h |  TYPE ID  |  NAME ID  |
           +-----+-----+-----+-----+
       04h |     RESOURCE SIZE     |
           +-----+-----+-----+-----+-----+-----+
       08h |   OBJECT  |        OFFSET         |
           +-----+-----+-----+-----+-----+-----+


     TYPE ID = DW  Resource type ID.
         The type of resources are:

             BTMP = Bitmap
             EMSG = Error message string
             FONT = Fonts

     NAME ID = DW  An ID used as a name for the resource when
     referred to.

     RESOURCE SIZE =  DD  The  number of  bytes the  resource
     consists of.

     OBJECT = DW  The number of the object which contains the
     resource.

     OFFSET  = DD  The  offset  within the  specified  object
     where the resource begins.





     Resident or Non-resident Name Table Entry


 The  resident and  non-resident name tables define the ASCII
 names  and  ordinal  numbers  for  exported  entries  in the
 module.  In  addition the first  entry in the resident  name
 table contains  the  module name. These tables  are  used to
 translate a procedure name  string into an ordinal number by
 searching for a matching name string.  The ordinal number is
 used  to  locate the  entry  point information in the  entry
 table.

 The resident name  table is kept  resident  in system memory
 while the  module is loaded.  It is intended to contain  the
 exported  entry point names  that  are frequently dynamicaly
 linked to  by  name.  Non-resident  names  are  not  kept in
 memory and are read from the  EXE file when a  dynamic  link
 reference  is made.  Exported  entry  point  names  that are
 infrequently dynamicaly linked to by  name  or are  commonly
 referenced  by  ordinal  number  should  be  placed  in  the
 non-resident name  table.  The trade off made for references
 by name is performance vs memory usage.

 Import  references  by  name  require  these  tables  to  be
 searched  to  obtain the entry point ordinal number.  Import
 references  by  ordinal  number  provide the fastest  lookup
 since the search of these tables is not required.

 The strings are CASE SENSITIVE and are NOT NULL TERMINATED.

 Each name table entry has the following format:

           +-----+-----+-----+-----+     +-----+-----+-----+
       00h | LEN |    ASCII STRING  . . .      | ORDINAL # |
           +-----+-----+-----+-----+     +-----+-----+-----+


     LEN = DB  String Length.
         This  defines the length  of the string in bytes.  A
         zero length indicates there  are no more  entries in
         table.  The length of  each  ascii  name  string  is
         limited to 127 characters.

         The high bit in  the LEN field (bit 7) is defined as
         an Overload bit.  This bit signifies that additional
         information is contained in  the  linear  EXE module
         and will be  used in the  future  for parameter type
         checking.

     ASCII STRING = DB  ASCII String.
         This is a variable length string  with  it's  length
         defined  in  bytes by the LEN field.  The string  is
         case case sensitive and is not null terminated.

     ORDINAL # = DW  Ordinal number.
         The ordinal number  in  an  ordered  index  into the
         entry table for this entry point.





     Entry Table


 The entry table contains object  and offset information that
 is used to resolve fixup  references  to  the  entry  points
 within this module.  Not all entry points in the entry table
 will be exported, some entry points will only be used within
 the module.  An  ordinal number is  used to  index  into the
 entry table.  The entry table entries  are numbered starting
 from one.

 The  list  of  entries  are compressed into 'bundles', where
 possible.  The entries within  each bundle are all the  same
 size.  A bundle starts with  a  count field  which indicates
 the number of entries in the bundle.  The  count is followed
 by a  type field  which identifies the  bundle format.  This
 provides  both  a  means  for  saving  space as  well  as  a
 mechanism for extending the bundle types.

 The type field  allows  the  definition of 256 bundle types.
 The following bundle types will initially be defined:

     Unused Entry.
     16-bit Entry.
     286 Call Gate Entry.
     32-bit Entry.
     Forwarder Entry.

 The bundled entry table has the following format:

           +-----+-----+-----+-----+-----+
       00h | CNT |TYPE | BUNDLE INFO . . .
           +-----+-----+-----+-----+-----+


     CNT = DB  Number of entries.
         This is the number of entries in this bundle.

         A  zero value for  the number of entries  identifies
         the  end of the entry  table.  There  is no  further
         bundle  information when  the number  of entries  is
         zero.  In other words the entry  table is terminated
         by a single zero byte.

     TYPE = DB  Bundle type.
         This  defines the  bundle type  which determines the
         contents of the BUNDLE INFO.

             The follow types are defined:

                 00h = Unused Entry.
                 01h = 16-bit Entry.
                 02h = 286 Call Gate Entry.
                 03h = 32-bit Entry.
                 04h = Forwarder Entry.
                 80h = Parameter Typing Information Present.
                     This   bit  signifies   that  additional
                     information  is contained in the  linear
                     EXE module  and  will  be  used  in  the
                     future for parameter type checking.


     The following is the format for each bundle type:

               +-----+-----+
           00h | CNT |TYPE |
               +-----+-----+

         CNT = DB  Number of entries.
             This is the number of unused entries to skip.

         TYPE = DB  0 (Unused Entry)

               +-----+-----+-----+-----+
           00h | CNT |TYPE |   OBJECT  |
               +-----+-----+-----+-----+
           04h |FLAGS|  OFFSET   |
               +-----+-----+-----+
           07h | ... |   . . .   |
               +     +     +     +


         CNT = DB  Number of entries.
             This is the  number of 16-bit  entries  in  this
             bundle.  The flags and offset value are repeated
             this number of times.

         TYPE = DB  1 (16-bit Entry)

             OBJECT = DW  Object number.
                 This is the object number for the entries in
                 this bundle.

             FLAGS = DB  Entry flags.
                 These  are the  flags for this entry  point.
                 They have the following definition.

                     01h = Exported entry flag.
                     F8h = Parameter word count mask.

             OFFSET = DW  Offset in object.
                 This is the  offset  in the  object for  the
                 entry point defined at this ordinal number.


               +-----+-----+-----+-----+
           00h | CNT |TYPE |   OBJECT  |
               +-----+-----+-----+-----+-----+
           04h |FLAGS|  OFFSET   | CALLGATE  |
               +-----+-----+-----+-----+-----+
           09h | ... |   . . .   |   . . .   |
               +     +     +     +     +     +


         CNT = DB  Number of entries.
             This is  the number of 286  call gate entries in
             this  bundle.  The  flags,  callgate, and offset
             value are repeated this number of times.

         TYPE = DB  2 (286 Call Gate Entry)
             The 286 Call Gate Entry  Point type is needed by
             the loader only  if ring  2 segments  are to  be
             supported.  286  Call  Gate  entries  contain  2
             extra bytes  which  are  used by  the  loader to
             store an LDT callgate selector value.

         OBJECT = DW  Object number.
             This is the  object  number  for the  entries in
             this bundle.

         FLAGS = DB  Entry flags.
             These are the flags  for this entry point.  They
             have the following definition.

                 01h = Exported entry flag.
                 F8h = Parameter word count mask.

         OFFSET = DW  Offset in object.
             This is the offset in the object  for  the entry
             point defined at this ordinal number.

         CALLGATE = DW  Callgate selector.
             The callgate  selector is a  reserved field used
             by the  loader  to store a  call  gate  selector
             value for references  to  ring  2  entry points.
             When a  ring 3 reference to a ring 2 entry point
             is  made,  the  callgate  selector with  a  zero
             offset is place in the relocation fixup address.
             The  segment  number  and  offset  in segment is
             placed in the LDT callgate.


               +-----+-----+-----+-----+
           00h | CNT |TYPE |   OBJECT  |
               +-----+-----+-----+-----+-----+
           04h |FLAGS|        OFFSET         |
               +-----+-----+-----+-----+-----+
           09h | ... |         . . .         |
               +     +     +     +     +     +

         CNT = DB  Number of entries.
             This is  the  number  of  32-bit entries in this
             bundle.  The flags and offset value are repeated
             this number of times.

         TYPE = DB  3 (32-bit Entry)
             The 32-bit Entry type will  only be  defined  by
             the linker when the offset in the object can not
             be specified by a 16-bit offset.

         OBJECT = DW  Object number.
             This  is  the object  number for the  entries in
             this bundle.

         FLAGS = DB  Entry flags.
             These are the  flags for this entry point.  They
             have the following definition.

                 01h = Exported entry flag.
                 F8h = Parameter dword count mask.

         OFFSET = DD  Offset in object.
             This is  the  offset in the object for the entry
             point defined at this ordinal number.

           +-----+-----+-----+-----+
       00h | CNT |TYPE | RESERVED  |
           +-----+-----+-----+-----+-----+-----+-----+
       04h |FLAGS| MOD ORD#  | OFFSET / ORDNUM       |
           +-----+-----+-----+-----+-----+-----+-----+
       09h | ... |    ...    |          ...          |
           +     +     +     +     +     +     +     +

     CNT = DB  Number of entries.
         This  is  the number  of forwarder  entries in  this
         bundle.  The  FLAGS,  MOD  ORD#,  and  OFFSET/ORDNUM
         values are repeated this number of times.

     TYPE = DB  4 (Forwarder Entry)

     RESERVED = DW 0
         This field is reserved for future use.

     FLAGS = DB  Forwarder flags.
         These  are the flags  for  this  entry  point.  They
         have the following definition.

             01h = Import by ordinal.
             F7h = Reserved for future use; should be zero.

     MOD ORD# = DW Module Ordinal Number
         This  is the index into the Import Module Name Table
         for this forwarder.

     OFFSET  /  ORDNUM = DD Procedure  Name Offset  or Import
     Ordinal Number
         If the FLAGS field indicates import by ordinal, then
         this field  is  the  ordinal number  into  the Entry
         Table of the target module, otherwise this  field is
         the  offset  into the Procedure Names Table  of  the
         target module.

 A Forwarder entry (type  = 4) is  an entry point whose value
 is an imported  reference.  When  a load  time  fixup occurs
 whose target is a forwarder, the  loader obtains the address
 imported by the forwarder and  uses that imported address to
 resolve the fixup.

 A forwarder  may refer  to an entry point  in another module
 which  is itself a  forwarder, so there  can be a  chain  of
 forwarders.  The  loader  will traverse the chain  until  it
 finds a non-forwarded entry point which terminates the chain
 ,  and  use  this to  resolve  the original fixup.  Circular
 chains are detected by the loader  and result in a load time
 error.  A  maximum of 1024 forwarders is allowed in a chain;
 more than this results in a load time error.

 Forwarders  are useful for merging and recombining API calls
 into  different  sets   of   libraries,   while  maintaining
 compatibility with applications.  For example, if one wanted
 to  combine MONCALLS,  MOUCALLS,  and VIOCALLS into a single
 libraries, one  could  provide entry  points  for  the three
 libraries  that   are  forwarders  pointing  to  the  common
 implementation.



     Module Format Directives Table


 The Module Format Directives Table is an optional table that
 allows additional options to  be specified.  It also  allows
 for  the extension of the  linear  EXE  format  by  allowing
 additional tables  of  information to be added to the linear
 EXE  module  without affecting the format  of the linear EXE
 header.  Likewise,  module format directives provide a place
 in   the   linear  EXE  module  for  'temporary  tables'  of
 information,  such as  incremental linking  information  and
 statistic information  gathered  on the module.  When  there
 are no module format directives for a linear EXE module, the
 fields  in  the linear EXE  header  referencing  the  module
 format directives table are zero.

 Each Module  Format Directive Table entry  has the following
 format:

           +-----+-----+-----+-----+-----+-----+----+----+
       00h | DIRECT #  | DATA LEN  |     DATA OFFSET     |
           +-----+-----+-----+-----+-----+-----+----+----+

     DIRECT # = DW  Directive number.
         The directive number specifies the type of directive
         defined.  This  can be used to  determine the format
         of  the  information  in  the  directive  data.  The
         following directive numbers have been defined:

             8000h = Resident Flag Mask.
                 Directive numbers with this bit set indicate
                 that the directive data is in  the  resident
                 area and will  be kept  resident  in  memory
                 when the module is loaded.

             8001h = Verify Record Directive. (Verify  record
             is a resident table.)
             0002h = Language Information Directive. (This is
             a non-resident table.)
             0003h = Co-Processor Required Support Table.
             0004h = Thread State Initialization Directive.

         Additional directives can be  added as needed in the
         future, as long as  they  do  not overlap previously
         defined directive numbers.

     DATA LEN = DW  Directive data length.
         This specifies the length in  byte of  the directive
         data for this directive number.

     DIRECTIVE OFFSET = DD  Directive data offset.
         This  is the offset to  the directive data for  this
         directive number.  It  is  relative to beginning  of
         linear EXE header for a resident table, and relative
         to  the  beginning of the EXE  file for non-resident
         tables.





     Verify Record Directive Table


 The Verify Record Directive Table  is an optional table.  It
 maintains a record  of  the pages in  the EXE file that have
 been  fixed up  and written back to the  original linear EXE
 module, along with the  module  dependencies used to perform
 these fixups.  This table  provides  an  efficient means for
 verifying the  virtual  addresses  required for the fixed up
 pages when the module is loaded.

 Each Verify Record entry has the following format:

           +-----+-----+
       00h |# OF ENTRY |
           +-----+-----+-----+-----+-----+-----+
       02h | MOD ORD # |  VERSION  | MOD # OBJ |
           +-----+-----+-----+-----+-----+-----+
       08h | OBJECT #  | BASE ADDR |  VIRTUAL  |
           +-----+-----+-----+-----+-----+-----+
       0Eh |   . . .   |   . . .   |   . . .   |
           +     +     +     +     +     +     +

     # OF ENTRY = DW  Number of module dependencies.
         This field specifies how many  entries there  are in
         the verify record directive table.  This is equal to
         the number of modules referenced by this module.

     MOD  ORD # = DW  Ordinal index  into  the  Import Module
     Name Table.
         This value is an ordered  index  in  to  the  Import
         Module Name Table for the referenced module.

     VERSION = DW  Module Version.

         This  is the version of  the  referenced module that
         the fixups  were originally performed.  This is used
         to insure the same version  of the referenced module
         is  loaded  that  was  fixed up  in this module  and
         therefore   the   fixups  are  still  correct.  This
         requires  the  version number  in  a  module  to  be
         incremented anytime the entry point offsets change.

     MOD # OBJ = DW  Module # of Object Entries.
         This field is used to  identify the number of object
         verify  entries  that   follow  for  the  referenced
         module.

     OBJECT # = DW  Object # in Module.
         This  field  specifies  the  object  number  in  the
         referenced module that is being verified.

     BASE ADDR = DW  Object load base address.
         This is  the  address that the object was  loaded at
         when the fixups were performed.

     VIRTUAL = DW  Object virtual address size.
         This field specifies the  total  amount  of  virtual
         memory required for this object.





     Per-Page Checksum


 The  Per-Page   Checksum   table   provides   space   for  a
 cryptographic  checksum for each  physical  page  in the EXE
 file.

 The checksum table is arranged such that the first entry  in
 the table corresponds to the first logical page of code/data
 in the EXE file (usually a preload page) and the  last entry
 corresponds to  the  last  logical  page  in  the  EXE  file
 (usually a iterated data page).

                     +-----+-----+-----+-----+
    Logical Page #1  |        CHECKSUM       |
                     +-----+-----+-----+-----+
    Logical Page #2  |        CHECKSUM       |
                     +-----+-----+-----+-----+
                               . . .

                     +-----+-----+-----+-----+
    Logical Page #n  |        CHECKSUM       |
                     +-----+-----+-----+-----+


     CHECKSUM = DD  Cryptographic checksum.





     Fixup Page Table


 The Fixup Page Table provides a simple  mapping of a logical
 page number to an  offset  into  the Fixup Record  Table for
 that page.

 This table is parallel to the Object Page Table, except that
 there is one  additional entry in this table to indicate the
 end of the Fixup Record Table.

 The format of each entry is:

                   +-----+-----+-----+-----+
  Logical Page #1  |  OFFSET FOR PAGE #1   |
                   +-----+-----+-----+-----+
  Logical Page #2  |  OFFSET FOR PAGE #2   |
                   +-----+-----+-----+-----+
                             . . .
                   +-----+-----+-----+-----+
  Logical Page #n  |  OFFSET FOR PAGE #n   |
                   +-----+-----+-----+-----+
                   |OFF TO END OF FIXUP REC|   This is equal to:
                   +-----+-----+-----+-----+   Offset for page #n + Size
                                               of fixups for page #n


     OFFSET FOR PAGE # = DD  Offset for fixup record for this
     page.
         This  field specifies the offset, from the beginning
         of the fixup record table, to the first fixup record
         for this page.

     OFF TO  END  OF FIXUP REC = DD  Offset to the end of the
     fixup records.
         This field specifies  the offset  following the last
         fixup record in the fixup record table.  This is the
         last entry in the fixup page table.

         The fixup records are kept in order by logical  page
         in the fixup record table.  This  allows the end  of
         each page's fixup records  is defined by  the offset
         for  the  next logical  page's fixup  records.  This
         last  entry provides  support of this mechanism  for
         the last page in the fixup page table.





     Fixup Record Table


 The  Fixup  Record Table contains entries  for all fixups in
 the linear EXE module.  The fixup records for a logical page
 are  grouped together and kept  in  sorted order by  logical
 page number.  The  fixups for  each page are  further sorted
 such that all external fixups  and internal selector/pointer
 fixups come before internal non-selector/non-pointer fixups.
 This allows  the  loader  to  ignore internal fixups  if the
 loader  is  able  to  load  all  objects  at  the  addresses
 specified in the object table.

 Each relocation record has the following format:

           +-----+-----+-----+-----+
       00h | SRC |FLAGS|SRCOFF/CNT*|
           +-----+-----+-----+-----+-----+-----+
   03h/04h |           TARGET DATA *           |
           +-----+-----+-----+-----+-----+-----+
           | SRCOFF1 @ |   . . .   | SRCOFFn @ |
           +-----+-----+----   ----+-----+-----+

         * These fields are variable size.
         @ These fields are optional.


     SRC = DB  Source type.
         The source type specifies the  size  and type of the
         fixup to  be  performed  on  the  fixup source.  The
         source type is defined as follows:

             0Fh = Source mask.
             00h = Byte fixup (8-bits).
             01h = (undefined).
             02h = 16-bit Selector fixup (16-bits).
             03h = 16:16 Pointer fixup (32-bits).
             04h = (undefined).
             05h = 16-bit Offset fixup (16-bits).
             06h = 16:32 Pointer fixup (48-bits).
             07h = 32-bit Offset fixup (32-bits).
             08h   =   32-bit  Self-relative   offset   fixup
             (32-bits).
             10h = Fixup to Alias Flag.
                 When the 'Fixup to Alias' Flag is  set,  the
                 source fixup refers to  the 16:16  alias for
                 the  object.  This is only  valid for source
                 types  of 2, 3, and 6.  For  fixups such  as
                 this, the linker and loader will be required
                 to   perform   additional   checks  such  as
                 ensuring that the  target  offset  for  this
                 fixup is less than 64K.

             20h = Source List Flag.

                 When  the  'Source  List'  Flag is set,  the
                 SRCOFF field  is compressed  to  a byte  and
                 contains the number of source offsets, and a
                 list  of source  offsets  follows the end of
                 fixup  record (after  the  optional additive
                 value).

     FLAGS = DB  Target Flags.
         The target flags specify how the target  information
         is interpreted.  The  target flags  are  defined  as
         follows:

             03h = Fixup target type mask.
             00h = Internal reference.
             01h = Imported reference by ordinal.
             02h = Imported reference by name.
             03h = Internal reference via entry table.
             04h = Additive Fixup Flag.
                 When set, an additive value trails the fixup
                 record (before the  optional  source  offset
                 list).

             08h = Reserved.  Must be zero.
             10h = 32-bit Target Offset Flag.
                 When  set, the  target  offset  is  32-bits,
                 otherwise it is 16-bits.

             20h = 32-bit Additive Fixup Flag.
                 When set,  the  additive value  is  32-bits,
                 otherwise it is 16-bits.

             40h = 16-bit Object Number/Module Ordinal Flag.
                 When  set,  the   object  number  or  module
                 ordinal number  is 16-bits, otherwise  it is
                 8-bits.

             80h = 8-bit Ordinal Flag.
                 When  set,  the  ordinal number  is  8-bits,
                 otherwise it is 16-bits.

     SRCOFF =  DW/CNT  = DB  Source  offset  or source offset
     list count.
         This field contains  either  an  offset  or  a count
         depending on the  Source  List Flag.  If the  Source
         List Flag is  set,  a list of source offsets follows
         the additive field and this field contains the count
         of  the  entries   in   the   source   offset  list.
         Otherwise, this is the single source offset for  the
         fixup.  Source offsets are relative to the beginning
         of the page where the fixup is to be made.

         Note that for fixups that  cross page  boundaries, a
         separate  fixup  record is  specified for each page.
         An offset is still used for the 2nd  page but it now
         becomes a negative offset since the fixup originated
         on  the  preceding page.  (For  example, if only the
         last one byte of a 32-bit address is on the page  to
         be fixed up, then the offset would  have  a value of
         -3.)

     TARGET DATA = Target data for fixup.
         The  format of the  TARGET  DATA  is  dependent upon
         target flags.

     SRCOFF1 - SRCOFFn = DW[]  Source offset list.
         This list is present if the  Source List Flag is set
         in the Target Flags field.  The number of entries in
         the  source offset list is defined in the SRCOFF/CNT
         field.  The  source  offsets  are  relative  to  the
         beginning of the  page where  the fixups are  to  be
         made.

               +-----+-----+-----+-----+
           00h | SRC |FLAGS|SRCOFF/CNT*|
               +-----+-----+-----+-----+-----+-----+
       03h/04h |  OBJECT * |        TRGOFF * @     |
               +-----+-----+-----+-----+-----+-----+
               | SRCOFF1 @ |   . . .   | SRCOFFn @ |
               +-----+-----+----   ----+-----+-----+

             * These fields are variable size.
             @ These fields are optional.


         OBJECT = D[B|W]  Target object number.
             This field is an index into the current module's
             Object Table to  specify  the target Object.  It
             is  a  Byte  value  when   the   '16-bit  Object
             Number/Module Ordinal  Flag' bit  in  the target
             flags field is clear and  a Word  value when the
             bit is set.


         TRGOFF = D[W|D]  Target offset.
             This  field  is  an  offset  into  the specified
             target  Object.  It  is  not  present  when  the
             Source Type  specifies a  16-bit Selector fixup.
             It  is  a  Word value when  the  '32-bit  Target
             Offset Flag'  bit  in the target flags field  is
             clear and a Dword value when the bit is set.

               +-----+-----+-----+-----+
           00h | SRC |FLAGS|SRCOFF/CNT*|
               +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
       03h/04h | MOD ORD# *| PROCEDURE NAME OFFSET*|     ADDITIVE * @      |
               +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
               | SRCOFF1 @ |   . . .   | SRCOFFn @ |
               +-----+-----+----   ----+-----+-----+

             * These fields are variable size.
             @ These fields are optional.


         MOD ORD # =  D[B|W]  Ordinal  index into the  Import
         Module Name Table.
             This value  is an ordered index in to the Import
             Module Name Table  for the module containing the
             procedure entry point.  It is a Byte value  when
             the '16-bit  Object Number/Module  Ordinal' Flag
             bit  in the target flags  field is  clear  and a
             Word  value  when  the  bit  is set.  The loader
             creates a table of pointers with each pointer in
             the  table  corresponds to the  modules named in
             the  Import  Module Name Table.  This  value  is
             used  by  the loader  to  index into  this table
             created by the  loader  to locate the referenced
             module.

         PROCEDURE NAME  OFFSET  =  D[W|D]  Offset  into  the
         Import Procedure Name Table.
             This   field   is  an  offset  into  the  Import
             Procedure Name Table.  It  is a Word  value when
             the  '32-bit  Target Offset  Flag'  bit  in  the
             target flags field  is clear and  a Dword  value
             when the bit is set.

         ADDITIVE = D[W|D]  Additive fixup value.
             This field exists in the fixup  record only when
             the 'Additive  Fixup  Flag'  bit  in  the target
             flags field is set.  When  the  'Additive  Fixup
             Flag' is clear the fixup record does not contain
             this  field  and is immediately followed by  the
             next fixup record (or  by the source offset list
             for this fixup record).

             This value is added to the address  derived from
             the  target entry point.  This field  is  a Word
             value when the '32-bit Additive Flag' bit in the
             target flags field is  clear  and a  Dword value
             when the bit is set.

               +-----+-----+-----+-----+
           00h | SRC |FLAGS|SRCOFF/CNT*|
               +-----+-----+-----+-----+-----+-----+-----+-----+
       03h/04h | MOD ORD# *|IMPORT ORD*|     ADDITIVE * @      |
               +-----+-----+-----+-----+-----+-----+-----+-----+
               | SRCOFF1 @ |   . . .   | SRCOFFn @ |
               +-----+-----+----   ----+-----+-----+

             * These fields are variable size.
             @ These fields are optional.


         MOD ORD  # = D[B|W]  Ordinal index  into  the Import
         Module Name Table.
             This value is an ordered index  in to the Import
             Module  Name Table for the module containing the
             procedure  entry point.  It is a Byte value when
             the '16-bit Object Number/Module  Ordinal'  Flag
             bit in the target flags  field is  clear  and  a
             Word  value  when  the  bit  is set.  The loader
             creates a table of pointers with each pointer in
             the table  corresponds  to the  modules named in
             the  Import Module  Name Table.  This  value  is
             used by the loader  to  index  into  this  table
             created  by the loader to locate the  referenced
             module.

         IMPORT ORD = D[B|W|D]  Imported ordinal number.
             This is the imported procedure's ordinal number.
             It is a Byte value when  the '8-bit Ordinal' bit
             in the target flags  field is set.  Otherwise it
             is  a Word value when the '32-bit Target  Offset
             Flag' bit in the target flags field is clear and
             a Dword value when the bit is set.

         ADDITIVE = D[W|D]  Additive fixup value.
             This field exists in the fixup  record only when
             the  'Additive Fixup Flag'  bit  in  the  target
             flags field is set.  When  the  'Additive  Fixup
             Flag' is clear the fixup record does not contain
             this field  and  is  immediately followed by the
             next fixup record (or  by the source offset list
             for this fixup record).

             This value is  added to the address derived from
             the  target entry point.  This field is  a  Word
             value when the '32-bit Additive Flag' bit in the
             target flags field  is  clear and a Dword  value
             when the bit is set.

               +-----+-----+-----+-----+
           00h | SRC |FLAGS|SRCOFF/CNT*|
               +-----+-----+-----+-----+-----+-----+
       03h/04h |  ORD # *  |     ADDITIVE * @      |
               +-----+-----+-----+-----+-----+-----+
               | SRCOFF1 @ |   . . .   | SRCOFFn @ |
               +-----+-----+----   ----+-----+-----+

             * These fields are variable size.
             @ These fields are optional.

         ENTRY #  =  D[B|W]  Ordinal  index  into  the  Entry
         Table.
             This field is an index into the current module's
             Entry  Table  to  specify the target Object  and
             offset.  It  is a Byte  value when  the  '16-bit
             Object Number/Module  Ordinal' Flag bit  in  the
             target flags field is  clear  and  a  Word value
             when the bit is set.

         ADDITIVE = D[W|D]  Additive fixup value.
             This field exists in the  fixup record only when
             the  'Additive Fixup  Flag'  bit  in the  target
             flags  field is set.  When the  'Additive  Fixup
             Flag' is clear the fixup record does not contain
             this  field and is  immediately followed  by the
             next fixup record (or by the source  offset list
             for this fixup record).

             This value  is added to the address derived from
             the  target  entry point.  This field is a  Word
             value when the '32-bit Additive Flag' bit in the
             target  flags  field  is clear and a Dword value
             when the bit is set.





  Import Module Name Table


 The import module name table defines the module name strings
 imported through dynamic link references.  These strings are
 referenced through the imported relocation fixups.

 To determine the  length  of the  import  module  name table
 subtract the import module name table offset from the import
 procedure  name  table offset.  These values are located  in
 the  linear EXE header.  The end  of the import module  name
 table  is  not  terminated by  a special  character,  it  is
 followed directly by the import procedure name table.

 The strings are CASE SENSITIVE and NOT NULL TERMINATED.

 Each name table entry has the following format:

           +-----+-----+-----+-----+     +-----+
       00h | LEN |    ASCII STRING  . . .      |
           +-----+-----+-----+-----+     +-----+

     LEN = DB  String Length.
         This defines the length of the string in bytes.  The
         length of each ascii name string is  limited  to 127
         characters.

     ASCII STRING = DB  ASCII String.
         This is a  variable  length string with it's  length
         defined in bytes by the  LEN  field.  The  string is
         case sensitive and is not null terminated.





     Import Procedure Name Table


 The import procedure name table defines  the  procedure name
 strings  imported  by  this  module   through  dynamic  link
 references.   These   strings  are  referenced  through  the
 imported relocation fixups.

 To determine the length  of the import procedure  name table
 add the fixup section size  to the  fixup page table offset,
 this computes the  offset to  the end of the  fixup section,
 then subtract the import procedure name table offset.  These
 values are located  in  the linear  EXE header.  The  import
 procedure name table is followed by the data pages  section.
 Since the  data pages  section is aligned  on a 'page  size'
 boundary, padded space  may  exist  between the  last import
 name  string  and the first page in  the data pages section.
 If this padded space exists it will be zero filled.

 The strings are CASE SENSITIVE and NOT NULL TERMINATED.

 Each name table entry has the following format:

           +-----+-----+-----+-----+     +-----+
       00h | LEN |    ASCII STRING  . . .      |
           +-----+-----+-----+-----+     +-----+

     LEN = DB  String Length.
         This defines the length of the string in bytes.  The
         length of each ascii  name  string is limited to 127
         characters.

         The high bit  in the LEN field (bit 7) is defined as
         an Overload bit.  This bit signifies that additional
         information  is  contained in the  linear EXE module
         and will  be  used in the future for  parameter type
         checking.

     ASCII STRING = DB  ASCII String.
         This is  a variable  length string  with it's length
         defined in bytes by the LEN  field.  The  string  is
         case sensitive and is not null terminated.





     Preload Pages


 The  Preload Pages section  is an  optional section  in  the
 linear EXE module that coalesces a 'preload page set' into a
 contiguous section.  The  preload page set can be defined as
 the set of first used pages in the module.  The preload page
 set can be specified by the application developer or can  be
 derived by a  tool that  analyzes the programs memory  usage
 while  it  is  running.  By grouping the  preload  page  set
 together, the preload pages can be read  from the linear EXE
 module with one disk read.

 The structure of  the preload pages is no different than  if
 they  were  demand  loaded.  They  are  non-iterated  pages.
 Their sizes are determined  by the Object Page Table entries
 that  correspond.  If  the  specified size is less than  the
 PAGE SIZE field given in the linear  EXE  module  header the
 remainder of the page is filled with zeros when loaded.

 All pages  begin on a  PAGE  OFFSET  SHIFT boundary from the
 base of the preload page section, as specified in the linear
 EXE  header.  The  pages are ordered by logical  page number
 within this section.

Note: OS/2 2.0 does not respect preload pages. Performance tests
showed that better system performance was obtained by not
respecting the preload request in the executable file.




     Demand Load Pages


 The   Demand   Loaded   Pages  section   contains   all  the
 non-iterated  pages  for a linear  EXE  module that are  not
 preloaded.  When  required,  the whole  page is loaded  into
 memory  from  the module.  The characteristics  of  each  of
 these pages is specified  in the  Object Page  Table.  Every
 page begins on a PAGE OFFSET SHIFT  boundary  aligned offset
 from the demand  loaded pages base specified  in the  linear
 EXE header.  Their  sizes are determined by the  Object Page
 Table  entries that correspond.  If  the  specified size  is
 less than the PAGE SIZE field given in the linear EXE module
 header the  remainder  of the page is filled with zeros when
 loaded.  The pages are ordered by logical page number within
 this section.




     Iterated Data Pages


 The Iterated Data Pages section contains all the pages for a
 linear EXE module that are iterated.  When required, the set
 of iteration records are loaded into  memory from the module
 and  expanded  to  reconstitute  the  page.  Every   set  of
 iteration records begins on  a PAGE OFFSET SHIFT offset from
 the  OBJECT ITER  PAGES  OFF  specified  in  the linear  EXE
 header.  Their sizes are determined by the Object Page Table
 entries  that correspond.  The  pages are ordered by logical
 page number within this section.

 This  record structure is used to describe the iterated data
 for an object on a per-page basis.

           +-----+-----+-----+-----+
       00h |#ITERATIONS|DATA LENGTH|
           +-----+-----+-----+-----+-----+
       04h |DATA BYTES |   . . .   | ... |
           +-----+-----+-----+-----+-----+

 Figure 19. Object Iterated Data Record (Iteration Record)

     #ITERATIONS = DW  Number of iterations.
         This specifies the number of  times that the data is
         replicated.

     DATA LENGTH = DW  The size of the data pattern in bytes.
         This specifies the number of bytes of  data of which
         the pattern consists.  The maximum size is  one half
         of the PAGE SIZE (given in the module header).  If a
         pattern exceeds  this value then the data page  will
         not be condensed into iterated data.

     DATA  =  DB  *  DATA  LENGTH  The  Data  pattern  to  be
     replicated.
         The next iteration record  will  immediately  follow
         the  last  byte of the  pattern.  The  offset of the
         next iteration record is easily calculated from  the
         offset  of  this record  by adding  the  DATA LENGTH
         field  and  the sizes  of the  #ITERATIONS  and DATA
         LENGTH fields.





     Debug Information


 The debug information  is  defined by  the debugger  and  is
 not controlled by the linear EXE format or linker.  The only
 data defined by the linear EXE format relative  to the debug
 information is  it's offset  in  the  EXE file and length in
 bytes as defined in the linear EXE header.

 To  support multiple debuggers the first word of  the  debug
 information is  a type  field which determines the format of
 the debug information.

           00h   01h   02h   03h   04h
           +-----+-----+-----+-----+-----+-----+-----+-----+
           | 'N' | 'B' | '0' |  n  |   DEBUGGER DATA  . . . .
           +-----+-----+-----+-----+-----+-----+-----+-----+


     TYPE = DB DUP 4 Format type.
         This defines  the type of debugger data  that exists
         in  the  remainder of  the  debug  information.  The
         signature consists  of  a  string  of four (4) ASCII
         characters:   "NB0"    followed    by   the    ASCII
         representation  for 'n'.  The  values  for  'n'  are
         defined as follows.

         These format types are defined.

             00h = 32-bit CodeView debugger format.
             01h = AIX debugger format.
             02h = 16-bit CodeView debugger format.
             04h = 32-bit OS/2 PM debugger (IBM) format.

     DEBUGGER DATA = Debugger specific data.
         The  format  of the debugger data  is defined by the
         debugger that is being used.

         The  values  defined  for  the  type  field are  not
         enforced by the  system.  It is  the  responsibility
         of  the  linker  or  debugging tools to  follow  the
         convention for the type field that is defined here.
