PDFXML Inspector is an Adobe AIR progra, it can view and edit Mars documents. Formerly the Mars Package Inspector, also allows you to make simple edits. This is a really nice tool for looking inside the file to see what is there and to experiment by adding to or changing the XML in a PDFXML document.

Requirements:
* Adobe AIR

The license of this software is Freeware, you can free download and free use this pdf software.