The variable pdcChangeLog maintains a sequence of elements, each representing a unique update to Active Directory that is exposed through the NT4 replication protocol ([MS-NRPC] section 3.5).

Though pdcChangeLog is an internal variable, its contents are sent over the network.

The pdcChangeLog variable is a sequence of CHANGELOG_ENTRY elements. These CHANGELOG_ENTRY elements are defined in [MS-NRPC] section