DDSIRTP26 — Inconsistent use of SEQUENCE_NUMBER_INVALID; for highestSentChangeSN

On initialization of the ReaderLocator, the highestSentChangeSN is set to SEQUENCE_NUMBER_INVALID which is not defined in this specification. In 8.4.7.2 RTPS StatelessWriter the function unsent_changes_reset is defined as resetting highestSentChangeSN to the value 0. Either define SEQUENCE_NUMBER_INVALID as being the value 0 and use it also in function unsent_changes_reset or use the value 0 instead of SEQUENCE_NUMBER_INVALID. Or, is there a good erason to make a distinction between SEQUENCE_NUMBER_INVALID and 0?