h_id	IN:	Access identifier returned by Hstartread, Hstartwrite, or Hnextread
	offset	IN:	Number of bytes to seek to from the origin
	origin	IN:	Position of the offset origin

	Purpose	Sets the access pointer to an offset within a data element.
	Return value	Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.
	Description	Sets the seek position for the next Hread or Hwrite operation by moving an access identifier to the specified position in a data element. The origin and the offset arguments determine the byte location for the access identifier. If origin is set to DF_START, the offset is added to the beginning of the data element. If origin is set to DF_CURRENT, the offset is added to the current position of the access identifier.
		Valid values for origin are: DF_START (the beginning of the file) or DF_CURRENT (the current position in the file).
		This routine fails if the access identifier if h_id is invalid or if the seek position is outside the range of the data element.