NAME
	OpenIFF -- prepare an IFFHandle to read or write a new IFF stream.
	           (V36)

   SYNOPSIS
	error = OpenIFF(iff, rwMode);
	D0              A0   D0

	LONG OpenIFF(struct IFFHandle *, LONG);

   FUNCTION
	Initializes an IFFHandle structure for a new read or write. The
	direction of the I/O is given by the value of rwMode, which can be
	either IFFF_READ or IFFF_WRITE.

	As part of its initialization procedure, OpenIFF() calls the client-
	supplied stream hook vector. The IFFStreamCmd packet will contain
	the following:

		sc_Command:	IFFCMD_INIT
		sc_Buf:		(Not applicable)
		sc_NBytes:	(Not applicable)

	This operation is permitted to fail. DO NOT write to this structure.

   INPUTS
	iff - pointer to IFFHandle structure. Starting with V39, this may be
	      NULL, in which case IFFERR_NOMEM is returned.
	rwMode - IFFF_READ or IFFF_WRITE

   RESULT
	error - contains an error code or 0 if successful

   SEE ALSO
	CloseIFF(), InitIFF(), <libraries/iffparse.h>