NAME
        ParentChunk -- get the nesting context node for the given chunk. (V36)

   SYNOPSIS
        parent = ParentChunk(contextNode);
        D0                   A0

        struct contextnode *parentchunk(struct contextnode *);

   FUNCTION
        Returns a context node for the chunk containing the chunk for the
        given context node. this function effectively moves down the context
        stack into previously pushed contexts. For example, to get a
        contextnode pointer for the enclosing form chunk while reading a data
        chunk, use: ParentChunk(CurrentChunk(iff)) to find this pointer.
        The contextnode structure contains information on the type of chunk
        and its size.

   INPUTS
        contextNode - pointer to a context node.

   RESULT
        parent - pointer to the enclosing context node or NULL if none.

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