The date selector is one of the predefined type extractors in iText pdf2Data, and aims to recognize a date string in a dozen of the common formats.
It gets an insight into which particular format should be looked for based on the content of the data field region.
As with all predefined type extractors it can be used together with the Pattern selector 

Best practices

The region of the data field should contain a full date, preferably one that cannot be ambiguously recognized. 
It is better to use 01-21-2022 to 01-01-2022, since the second one is good enough for both dd-mm-yyyy and mm-dd-yyyy formats

Expert mode keyword:

List of selectors