NAME
        ExitHandler -- add an exit handler to the iffhandle context. (v36)

   SYNOPSIS
        error = ExitHandler(iff, type, id, position, handler, object);
        D0                  A0   D0    D1  D2        A1       A2

        long exithandler(struct iffhandle *, long, long, long,
                         struct hook *, aptr object(;

   FUNCTION
        Installs an exit handler vector for a specific type of chunk into the
        context for the given iffhandle structure. type and id are the longword
        identifiers for the chunk to handle. The handler is a client-supplied
        standard hook structure, properly initialized. position tells
        where to put the handler in the context. The handler will be called
        just before the parser exits the given chunk in the "pause" parse
        state. The IFF stream may not be positioned predictably within the
        chunk. The handler will execute in the same context as whoever
        called parseiff(). the handler will be called (through the hook)
        with the following arguments:

                A0:     the hook pointer you passed.
                A2:     the 'object' pointer you passed.
                A1:     pointer to a long containing the value
                        IFFCMD_EXIT.

        The error code your call-back routine returns will affect the parser
        in three different ways:

        Return value            Result
        ------------            ------
        0:                      Normal success;  parseiff() will continue
                                through the file.
        IFF_RETURN2CLIENT:      parseiff() will stop and return the value 0.
                                (StopChunk() is internally implemented using
                                this return value.)
        Any other value:        parseiff() will stop and return the value
                                you supplied. This is how errors should be
                                returned.

   INPUTS
        iff - pointer to iffhandle structure.
        type - type code for chunk to handle (ex. "ILBM").
        id - identifier code for chunk to handle (ex. "CMAP").
        position - local context item position. One of the IFFSLI_#? codes.
        handler - pointer to hook structure.
        object - a client-defined pointer which is passed in A2 during call-
                 back.

   RESULT
        error - 0 if successful or an IFFERR_#? error code if unsuccessful.

   BUGS
        Returning the values IFFERR_EOF or IFFERR_EOC from the call-back
        routine *may* confuse the parser.

        There is no way to explicitly remove a handler once installed.
        However, by installing a do-nothing handler using IFFSLI_TOP,
        previous handlers will be overridden until the context expires.

   SEE ALSO
        entryhandler(), storelocalitem(), storeitemincontext(),
        <utility/hooks.h>, <libraries/iffparse.h>