VxD: Determine the size of file segments for code and data and their location - header

Question

I have a sample VxD code here that just shows a message box whenever a DOS prompt is opened or closed under Windows 98.
What I need to know is which fields determine the code segment or page, the data segment, and their size in bytes or pages.
It is actually an old Linear Executable EXE that for VxDs is supposedly always has a signature of "LE".
So far I know that:
MemPagesCtr tells how many blocks there are of MemPageSZ bytes, that I can make 512 bytes in size and still be sane until now.
LastPageBytes says how many bytes the very last portion of the VxD file has, which can be less or probably equal than MemPageSZ.
Which header fields indicate which of the pages is the code, data, or are they always in the same sequence for VxD LE EXE? And how to know where the actual code entry and data start?
;http://master.dl.sourceforge.net/project/api-simple-completa/api.7z?viasf=1
%include "../../../PC/BIOS/WinAPI/EXE/PE/snippets/DOS_Stubs/NASM/DOS_Stub_classic0xB0.asm"
PE_header:
LE_header:
LE_header_start:
LE_header_0x00_Signature db 'LE'
LE_header_0x02_ByteOrder db 0 ;0 Little or Big Endian
LE_header_0x03_WordOrder db 0 ;0 Little or Big Endian
LE_header_0x04_FormatLevel dd 0
LE_header_0x08_CPUType dw 2 ;1 286+, 2 386+, 3 486+, 4 586+, 20h i860 N10+, 21h N11+, 40h MIPS Mark I+ (R2000, R3000), 41h MIPS Mark II+ (R6000), 42h MIPS Mark III+ (R4000)
LE_header_0x0A_TargetOS dw 4 ;1 OS/2, 2 Win16, 3 DOS 4x, 4 Win386
LE_header_0x0C_ModuleVersion dd 0
LE_header_0x10_Flags dd 101000000000000000b ;
LE_header_0x14_MemPagesCtr dd 3
LE_header_0x18_InitialCS dd 0
LE_header_0x1C_InitialEIP dd 0 ;Explicar cómo encuentra y carga las secciones y direcciones de código y datos el VxD
LE_header_0x20_InitialSS dd 0
LE_header_0x24_InitialESP dd 0
LE_header_0x28_MemPageSZ dd 512 ;Tamaño de datos
LE_header_0x2C_LastPageBytes dd 0x31
LE_header_0x30_FixUpSectionSZ dd 0x85
LE_header_0x34_FixUpSectionCheck dd 0
LE_header_0x38_LdrSectionSZ dd 0x69
LE_header_0x3C_LdrSectionCheck dd 0
LE_header_0x40_ObjectTableOffset dd 0xC4 ;from where?
LE_header_0x44_ObjectTableEntries dd 3
LE_header_0x48_ObjectPageMapOffset dd 0x10C
LE_header_0x4C_ObjectIterDataMapOff dd 0 ;always 0 for VxD?
LE_header_0x50_RsrcTableOffset dd 0
LE_header_0x54_RsrcTableEntries dd 0
LE_header_0x58_ResidentTableOffset dd 0x118
LE_header_0x5C_EntryTableOffset dd 0x123
LE_header_0x60_ModulDirectivesTable dd 0 ;always 0 for VxD?
LE_header_0x64_ModulDirectivesEnts dd 0
LE_header_0x68_FixupPageTblOffset dd 0x12D
LE_header_0x6C_FixupRecordTable dd 0x13D
LE_header_0x70_ImportModulesTable dd 0x1B2
LE_header_0x74_ImportModulesCount dd 0
LE_header_0x78_ImportProcTable dd 0x1B2
LE_header_0x7C_PerPageChecksums dd 0
LE_header_0x80_DataPagesOffset dd 0x400 ;0x1000; 0x400;0x2E0;0x1000 ;inicio de código y datos después de la cabecera
LE_header_0x84_PreloadPageCount dd 1
LE_header_0x88_NonResidentNames dd 0x1434
LE_header_0x8c_NonResidentNamesLen8 dd 15 ;in bytes
LE_header_0x90_NonResidentNamesChk dd 0
LE_header_0x94_AutomaticDataObject dd 0
LE_header_0x98_DebugInformationOff dd 0
LE_header_0x9C_DebugInformationLen dd 0
LE_header_0xA0_PreloadInstPagesNum dd 0
LE_header_0xA4_DemandInstancePgsNum dd 0
LE_header_0xA8_ExtraHeapAllocation dd 0
LE_header_0xAC dd 0
;File Offset 0x160, LE header offset 0xB0
;INIT:
;INIT:
;INIT:
;INIT:
times 16 db 0
dd 0x4000000
dd 0xE8
dd 0
dd 0x2045
dd 1
dd 1
db "LCOD'",0,0,0
dd 0
dd 0x2005
dd 2
dd 1
db "PCOD1",0,0,0
dd 0
dd 0x2023
dd 3
dd 1
db "PDAT"
dd 0x10000
db 0,0,2,0
db 0,0,3,0
db 7
db "MESSAGE"
db 0,0,0,1,3,1,0,3,0,0,0,0,0,0,0,0
db 0,0x60,0,0,0,0x75,0,0,0,0x75,0,0,0,7,0,0xE1
db 0,2,0x20,0,0x27,0,0x1F,1,0x5F,0,0x65,0,0x69,0,0x6D,0
db 0x71,0,0x75,0,0x79,0,0x7D,0,0x81,0,0x85,0,0x89,0,0x8D,0
db 0x91,0,0x95,0,0x99,0,0x9D,0,0xA1,0,0xA5,0,0xA9,0,0xAD,0
db 0xB1,0,0xB5,0,0xB9,0,0xBD,0,0xC1,0,0xC5,0,0xC9,0,0xCD,0
db 0xD1,0,0xD5,0,0xD9,0,0xDD,0,7,0,0x61,0,2,0,0,7
db 0,0x5B,0,1,0x61,0,7,0,0x18,0,1,0x50,0,7,0,0x21
db 0,3,0x1F,0,7,0,0x11,0,3,0,0,7,0,1,0,3
db 15,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,32,32,32,32
db "MESSAGE_DDB",0,32,0X40,0X31,0
db 32,32,32,"CLASS",0,"'RCODE",0
db 0,0,32,32,32,"PRELOAD DISCARDABLE",0,0
db "CONFORMING",0,0,0,0,0,0,0,0,0,0,0,0
;times 0xD20 db 0
;align 0x1000
align 0x400
;END:
;END:
;END:
;END:
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;0x1000 en el archivo tiene .00000000
;de base en HIEW, por qué?
;;
;INIT: Page 0
;INIT: Page 0
;INIT: Page 0
;INIT: Page 0
db 0,0,0,0,0,4,0,0,1,0,0,0,"MESSAGE"
db 32,0,0,0,0x80,0,0,0,0,0,0,0,0
times 16 db 0
dd 0,0,0
db "verPP",0,0,0
db "1vsR2vsR3vsR",0x83,0xE8,7,0x83,0xF8,0x21,0x73,7,-1,0x24,0x85,0,0,0,0,0xF8
db 0xC3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
times 16*7 db 0
db 0,0,0,0,0,0xCC,0xCC,0xCC,0,0,0,0,0,0,0,0
;times 16*17 db 0
%define round(n, r) (((n+(r-1))/r)*r)
align 512
;END: Page 0
;END: Page 0
;END: Page 0
;END: Page 0
;align 512
;_s:
;times (512-_s) db 0
;dd round(_s,512)
;times (512-$$) db 0
;INIT: Page 1
;INIT: Page 1
;INIT: Page 1
;INIT: Page 1
bits 32
mov ecx,0 ;xor ecx,ecx
;xor ecx,ecx
db 0xCD,0x20,3,0,1,0 ;VMMcall Get_Sys_VM_Handle
mov eax,0x30
mov edi,0
xor esi,esi
xor edx,edx
;db 0xCD,0x20,4,0,17,0 ;VxDcall VMCPD.Set_CR0_State ;17 en vez de 0x17, probar valores WORD o DWORD
db 0xCD,0x20,4,0,0x17,0 ;VxDcall SHELL.Message
ret
mov ecx,0
db 0xEB,0xDE ;jmps .5
;times 9 db 0
;times 16*29 db 0
align 512
;END: Page 1
;END: Page 1
;END: Page 1
;END: Page 1
;INIT: Page 2
;INIT: Page 2
;INIT: Page 2
;INIT: Page 2
db "VxD MessageBox",0
db "A VM is created",0
db "A VM is destroyed",0
;db "SEC",0x0B
;db "MESSAGE_DDB",0,0,0
;END: Page 2
;END: Page 2
;END: Page 2
;END: Page 2