This article shows how to use regular expressions to make powerful string matches
The regex operator can be used to match to any string property
regex(PropertyName, "expression")
Here are a few examples:
regex(assetName, "[A-Z].*")
returns true if the asset name starts with a capital letter
regex(assetName, "/[A-Z].*/i")
We're not going to cover the full syntax of regular expressions here, but this is a good cheatsheet.