To search for a chunk in an open RIFF file, use mmioDescend with the MMIO_FINDCHUNK parameter. Also set the ckid field of the MMCKINFO structure referenced by pckinfo to the four-character code of the chunk you want to search for.
If you are searching for a RIFF or LIST chunk, the mmioDescend function sets the ckid field of the MMCKINFO structure. Set the fccType field to the four-character code of the form type or list type of the chunk.