[Feature Request] Dates in Label Expressions

Is it possible to introduce the concept of (something like) `$system{today}` in order to enable a "Printed/Exported on" label to be produced.

I have other means of "version control" for exported/printed views, but it would be great if a "dynamic" "today" date could be included for each one.

The issue requests date expressions in label expressions so printed or exported views can show a dynamic “today” date. No files, tests, or entry points are identified; determine where label expressions and printed/exported views are handled, then verify that the generated output contains the current date.

Written by the indexing model from the issue text.