On Sun, Feb 21, 2016 at 3:19 AM, Peter Nabbefeld <peter.nabbefeld@gmx.de> wrote:

I'm looking for the DTDs for XMI 1.x files (UML profile), especially for
XMI 1.2 to XMI 1.4.

On second thought, what exactly are you looking for? I don't think there ever was an XMI 1.4, was there? Are you looking for a UML 1.4 DTD, as opposed to XMI 1.4? What do you need the files for? That might help figure out exactly what you need. My memories of this are dim, but I'm not 100% sure there even is a separate XMI DTD.

The OMG numbering scheme is a bit confusing because they've got separate versions for XMI, MOF, and UML and they don't necessarily proceed in an easily understandable order.

I've already tried to find those, but they even seem to be unavailable
at OMG.

It looks like they've moved the ancient versions of the specs to "the vault" http://www.omg.org/technology/documents/vault.htm#M&M

Although the machine readable artefacts are often included in the PDF specs, a key phrase to look for is "supporting files" which often have the machine readable files separately. For example, 
this: 
    http://www.omg.org/cgi-bin/doc?formal/01-04-03 
is ZIP file containing the UML 1.3 and MOF 1.3 DTDs.

There's a complete list of the OMG documents available here: 
    ftp://ftp.omg.org/pub/docs/doclist.txt

There's another page with lots of XMI information (in German) here:
    http://www.jeckle.de/xmi.htm

Good luck! I used to know this stuff backwards and forwards, but fortunately it's mostly a dim distant memory now. :-)

Tom