XSLT - merging two not opened files

[Pierre-de-la-Verre]

The common usage of XSLT is to open an XML and to apply an XSLT to the opened file.

Now I played around with an XSLT which uses (two) external, not opened XML (a.xml and b.xml) and "merges" them. In common, it works, but I don't understand the default output-path of the transformation. There are some possible situations for an output-path

• I open "some.xml" and apply the XSLT: it seem to use the path of "some.xml"
• I press "New file" and apply the XSLT: it seem to use the path of the first file in the "MRU-list", on top right
• I press "New file", delete the first entry in the MRU-list and apply the XSLT: it seem to use the path of the XSLT

What's the intended behaviour?

merge_external.zip