What syntax of regular expressions is used in Vantage Advanced Designer?
There are two different syntaxes used in the Advanced Designer.
The first type is in the Fields tab:
It's a common syntax and its description is noted below the editor. It could be tested on the following web page: https://regex101.com/
The second type of regular expression is used in the Extraction Rules activity for the elements:
It is the same that was used in the ABBYY FlexiLayout Studio. The guide on how to use can be found in the ABBYY FlexiLayout Studio Help: Character String