EDX is an open standard. Content of EDX can be read/created using any code (based on spec) or with use of EDX-SA Utilities (www.edx-sa.com).
As far as Mentor provided content in EDX, there are portions of the data that are encrypted (e.g. native Xpedition data for both design and library) these data cannot be edited using EDX-SA. Please let me know which use-cases you would like to address?