Glossary
Dirty hive
A registry hive whose header sequence numbers differ, meaning some changes still live only in its .LOG1/.LOG2 transaction logs and must be replayed.
A hive is dirty when the primary and secondary sequence numbers in its base block (offsets 4 and 8) differ: Windows had started writing changes that were logged in the transaction logs (.LOG1, .LOG2) but not yet merged into the primary file (libregf, msuhanov/regf).
For BAM, those pending writes are often the most recent executions. Always collect the logs with the SYSTEM hive, replay them (for example with rla.exe or Registry Explorer) and parse the result. The BAM/DAM Parser warns when a hive is dirty but does not replay logs itself.