NAME
	InitIFF -- initialize an IFFHandle structure as a user stream. (V36)

   SYNOPSIS
	InitIFF(iff, flags, streamHook);
	        A0   D0     A1

	VOID InitIFF(struct IFFHandle *, LONG, struct Hook *);

   FUNCTION
	Initializes an IFFHandle as a general user-defined stream by
	allowing the user to declare a hook that the library will call to
	accomplish the low-level reading, writing, and seeking of the stream.
	Flags are the stream I/O flags for the specified stream; typically a
	combination of the IFFF_?SEEK flags.

	The stream vector is called with the following arguments:

		A0:	pointer to streamhook.
		A2:	pointer to IFFHandle structure.
		A1:	pointer to IFFStreamCmd structure.

	The IFFStreamCmd packet appears as follows:

		sc_Command:	Contains an IFFCMD_#? value
		sc_Buf:		Pointer to memory buffer
		sc_NBytes:	Number of bytes involved in operation

	The values taken on by sc_Command, and their meaning, are as follows:

	IFFCMD_INIT:
		Prepare your stream for reading. This is used for certain
		streams that can't be read immediately upon opening, and need
		further preparation. (The clipboard.device is an example of
		such a stream.)  This operation is allowed to fail;  any
		error code will be returned directly to the client. sc_Buf
		and sc_NBytes have no meaning here.
	IFFCMD_CLEANUP:
		Terminate the transaction with the associated stream. This
		is used with streams that can't simply be closed. (Again,
		the clipboard is an example of such a stream.)  This
		operation is not permitted to fail;  any error returned will
		be ignored (best to return 0, though). sc_Buf and sc_NBytes
		have no meaning here.
	IFFCMD_READ:
		Read from the stream. You are to read sc_NBytes from the
		stream and place them in the buffer pointed to by sc_Buf.
		Any (non-zero) error returned will be remapped by the parser
		into IFFERR_READ.
	IFFCMD_WRITE:
		Write to the stream. You are to write sc_NBytes to the
		stream from the buffer pointed to by sc_Buf. Any (non-zero)
		error returned will be remapped by the parser into
		IFFERR_WRITE.
	IFFCMD_SEEK:
		Seek on the stream. You are to perform a seek on the stream
		relative to the current position. sc_NBytes is signed;
		negative values mean seek backward, positive values mean seek
		forward. sc_Buf has no meaning here. Any (non-zero) error
		returned will be remapped by the parser into IFFERR_SEEK.

	All errors are returned in D0. A return of 0 indicates success.
	UNDER NO CIRCUMSTANCES are you permitted to write to the IFFStreamCmd
	structure.

   INPUTS
	iff - pointer to IFFHandle structure to initialize.
	flags - stream I/O flags for the IFFHandle.
	streamHook - pointer to Hook structure.

   SEE ALSO
	<utility/hooks.h>, <libraries/iffparse.h>