CHANGELOG_ENTRY is a concrete type that is defined in [MS-NRPC] section, with more information in [MS-ADTS] section The abstract variable dc.pdcChangeLog is a sequence of CHANGELOG_ENTRY. The following two fields within this type are used in specifying IDL_DRSGetNT4ChangeLog server behavior:

ChangeLogEntrySize: A DWORD containing the size, in bytes, of the CHANGELOG_ENTRY structure.

SerialNumber: A LARGE_INTEGER containing the serial number of the update represented in this CHANGELOG_ENTRY.