Reference

XtLastTimestampProcessed(3x) on Linux

The text 8599c5fa289e, as Debian 2.2 (Potato), Debian 2.1 (Slink), Debian 2.0 (Hamm), Debian 1.3 (Bo) shipped it.

last event, last timestamp processed

XtLastTimestampProcessed(3x) on Linux now