Your samples are watermarks originally added to printed and (more recently) electronically distributed scripts.
The code is designed to identify who received that particular copy of the script. Their use as a security feature is grossly overrated in the industry.
It is normally added by the production office or the script coordinator.
It is a feature of Final Draft, WriterDuet, Highland 2, Fade In (and other screenwriting) software. It can also be added by Studio Binder, Scenechronize and other production management software.
Most implementations of the watermark are now trivially easy to remove on pdf files. But they were difficult to defeat back in the days of printed scripts that were then scanned.
The watermark also incidentally allows production staff to return pages (or sides) found lying around on-set to their owner if the watermark is the Actor's name.
The watermark is never used for revision control. The title page and page header is used to identify revised pages of the script.