The CHPX is stored within Character FKPs and within the STSH in STDs for paragraph style and character style entries.
| b10 | b16 | field | type | size | bitfield | comments |
| 0 | 0 | cb | byte | count of bytes of following data in CHPX. | ||
| 1 | 1 | grpprl | character array | a list of the sprms that encode the differences between CHP for a run of text and the CHP generated by the paragraph and character styles that tag the run. |