INT 21 U - IFSHLP.SYS - GET ENTRY POINT                                         
	AH = 3Fh
	BX = file handle for device "IFSsee Installable File System$HLP$"
	CX = 0008h (size of buffer in bytes)
	DS:DX -> buffer for entry point record (see #01415)
Return: CF clear if successful
	    AX = number of bytes actually read (0 if at EOF before call)
	CF set on error
	    AX = error code (05h,06h) (see #01680 at AH=59h/BX=0000h)
Program: IFSHLP.SYS is a support driver for Microsoft Windows for Workgroups
SeeAlso: AX=4402h"IFSHLP"


Format of IFSHLP.SYS entry point record:
Offset	Size	Description	(Table 01415)
 00h  4 BYTEs	(call) required signature if called via IOCTL
			70h E9h 34h 37h for Windows 3.11
			70h E9h 35h 37h for Windows 3.11
		(ret) signature 34h 37h 70h EFh (Windows 3.11)
		(ret) signature 35h 37h 70h EFh (Windows95)
 04h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	(ret) pointer to FAR call entry point (see #01416)


(Table 01416)
Call IFSHLP.SYS entry point with:
	STACK:	WORD	function number (00h-0Ch)
			00h get ??? data
			01h set interrupt intercepts (trap)
			02h remove interrupt intercepts (untrap)
			03h ??? LPT2
			04h ??? LPT1
			05h revector INT 2F to trap and remove trap for others
			06h set ??? flag
			07h clear ??? flag
			08h get ??? flag word
			---Windows 3.11 only---
			09h ???
			0Ah ???
			0Bh ???
			0Ch get ???
---if function 00h---
Return: DX:AX -> ??? data (see #01417)
	BX destroyed
---if function 01h---
	STACK:	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	new intercept (trap) address
Return: AX = status
	    0000h successful
	    0001h failed (already set)
		DX = 0000h
	BX destroyed
Note:	the trap handler is called with a function number in BX, and the
	  original BX on top of the stack; a null handler must perform a
	  POP BX and an IRET
---if function 02h---
Return: AX = status
	    0000h successful
	    0001h failed (not set)
	DX = 0000h
	BX destroyed
---if function 03h,04h---
	STACK:	WORD	???
Return: AX = 0000h
	DX = 0000h
	BX destroyed
---if function 05h---
	???
Return:	BX destroyed
---if function 06h---
Return: AX = 0001h and DX = 0000h if already set
	AX,DX unchanged if successful
	BX destroyed
---if function 07h---
Return: AX = 0001h and DX = 0000h if not set
	AX,DX unchanged if successful
	BX destroyed
---if function 08h---
Return: DX = 0000h
	AX = flags
	    bit 0: set/cleared by functions 06h and 07h
	    bit 1: trap is currently set (refer to functions 01h/02h)
	BX destroyed
---if function 09h---
Return: AX = status
	    0000h successful
	    0001h failed (already called)
	BX destroyed
---if function 0Ah---
	STACK:	WORD	???
	???
Return:	BX destroyed
---if function 0Bh---
Return: AX = status
	    0000h successful
	    0001h failed (not set)
	BX destroyed
---if function 0Ch---
Return: AX = 0000h
	ES:BX -> ??? data
---if function > 0Ch---
Return: AX = 0001h
	DX = 0000h
	BX destroyed


Format of IFSHLP ??? data:
Offset	Size	Description	(Table 01417)
 00h	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	-> DOS Swappable Data AreaThe portion of the DOS data segment containing all of the variables used internally by DOS to record the state of a function call in progress.  See also INT 21h Function 5D06h and INT 21h Function 5D0Bh. (see #01687,#01689)
 02h	WORD	??? offset in DOS data segment?
 04h	WORD	offset in DOS data segment of current-PSP WORD
 06h	WORD	???
 08h	WORD	???
 0Ah	WORD	???
 0Ch	DWORDDoubleword; four bytes.	 Commonly used to hold a 32-bit segment:offset or selector:offset address.	-> DOS List of ListsAn internal DOS table of lists and other tables through which most DOS-internal data structures may be reached.  See INT 21h Function 52h. (see #01627)
 10h	???
SeeAlso: #01416