This is not so much a parser but a way to extract data from the source object itself directly. For HTML pages, this can be the name of a field on the Sitecopy page entity itself. This is how you would access the page title or path alias override, for instance. You can also configure other fields and use them in this manner. For CSV files, there is no special data that you cannot get with the CSV single-value parser instead.
It only has one property “Data Object Property”. At the moment, this is a text field into which you put the name of the field. In the future, we hope to change this to a drop-down of properties.