Edited Unassigned: Generate binary identical file for same input [9399]

Currently when I generate a workbook with a sheet and save it as .xlsx and then use the same code again I get two files with different content.
I would like to get exactly the same file, so I can easily (e.g. for version control) see that no changes occurred in the spreadsheet.

When I renamed the generated files to .zip and extracted those I noticed the only differences were:
* a different file name for the .psmdcp file generated in package\services\metadata\core-properties
* the content of the .psmdcp file contains one element whose value changes 'dcterms:modified'
* the content of _rels/.rels:
* Relationship IDs that are different (even for files that are the same, such as workbook.xml) for some, but identical for others (e.g. app.xml)
* the different file name of the .psmdcp file

My questions/requests:
* I believe the file name is a GUID. Would it be possible to always use the same one for the .psmdcp file?
* I do not see any usage of the relationship ID. Would it be possible to use the same IDs for all Relationships always?
* Is there some way we can set/force the 'dcterms:modified' element?