Pick an XML document to use as a source for a crosswalk. Based on the structure of the document, select elements that define records. Then select the elements and attributes that contain field data.
Make selections via XPath expressions or by a pick-list based on the document. (Show selected data in preview table.)
Use crosswalk.edit to support editing of the data source in the project navigator. (By leveraging the built-in EMF editing support, It is possible that copy/paste operations will work between crosswalks too.)
Note: Tools like JHOVE generate deeply nested XML structures based on file structures. The XPath approach to selecting records can work find for nested information. Each nested element is simply treated as another instance of a record.
Note: Mapping XML data sources raises the possibility of passing XML fragments as data within the crosswalk. This would be useful in populating mixed content output elements, such as the mods:accessCondition.