custom meta-tags at PDF Files

[Thommynat0r]

Over the years I accumulated many PDF ebooks. Now I want to organize them more useful. Until now I organized it in the Windows Explorer with folders as categories. But now I wanted to add custom Meta Tags, the same like author, title but own categories like booktype, field, subcategory etc. I have done this with the program "PDF Explorer". If I open now the PDF File with Adobe Acrobat (File->properties->custom), I can find these custom meta tags. But if i open the file with Calibre or Windows Explorer, I cannot find these custom Tags. Of course in calibre I can create new custom tags, but thats not the point, because Calibre don't modify the file itself.

Is it possible to add the function in Calibre to recognize the User-defined keys / Meta Tags?

I'm talking about chapter 3.2.1 in this file:
http://www.adobe.com/content/dam/Ado...ationPart3.pdf