Format of MRCREQUEST structure:
Offset	Size	Description	)
 00h	DWORD	pointer to source buffer
 04h	WORD	size of source buffer (0000h = 64K)
 06h	WORD	(UpdateCompress only)
		(call) offset in source buffer of beginning of changed data
		(ret) offset in destination buffer of beginning of changed
			  compressed data
 08h	DWORD	pointer to destination buffer
		must contain original compressed data for UpdateCompress
 0Ch	WORD	size of destination buffer (0000h = 64K)
		any compression: size of buffer for compressed data
		standard decompression: number of bytes to be decompressed
		incremental decompression: number of byte to decompress now
		(ret) actual size of resulting data
 0Eh	WORD	client compressed data storage allocation size
 10h	DWORD	incremental decompression state data
		set to 00000000h before first incremental decompression call
Notes:	the source and destination buffers may not overlap
	the source and destination buffer sizes should normally be the same
	application should not update the contents of the MRCREQUEST structure
	  between incremental decompression calls