The actual elements of data referenced by the CTOC chunk are stored in a compound file Element Group (CGRP) chunk. The CGRP chunk contains all the compound file elements, concatenated together into one contiguous block of data. Some of the elements in the CGRP chunk might be unused, if the element was marked for deletion or was altered and stored elsewhere within the CGRP chunk.
Elements within the CGRP chunk are of arbitrary size and can appear in a specific or arbitrary order, depending upon the file format definition. Each element is identified by a corresponding CTOC table entry.
Using the standard RIFF notation, the CGRP chunk is defined as follows:
<CGRP-chunk> CGRP([<compound file element>]...)