NAME
        PopChunk -- pop top context node off context stack. (V36)
   SYNOPSIS
        error = PopChunk(iff);
        D0               A0
        long popchunk(struct iffhandle *);
   FUNCTION
        Pops top context chunk and frees all associated local context items.
        The function is normally called only for writing files and signals
        the end of a chunk.
   INPUTS
        iff - pointer to iffhandle structure.
   RESULT
        error - 0 if successful or an IFFERR_#? error code if unsuccessful.
   SEE ALSO
        pushchunk(), <libraries/iffparse.h>