Besides XML, I have one issue:

1. What if the Extension is given without the fullstop - just "PAR", but then just "PAR" can be mistaken with something else. But we can't look at it as the last string "PAR$" cause there can be some bracket etc.

I have no real idea how to solve this. Better to send to Henk for review as well - even though it will take some time...

I'm fine with it and let's see if Henk has any idea how to address my comment in PR...

We should add an elseif for another (unknown) extension, then it can just issue a warning that we detected an unknown extension.

MINOR:
I would replace the regular expressions by a single one, then you can do the regexp once outside the if statement.

hasKnownExtension = ~isempty(regexpi(lastElement,'.(dcm|ima|xml|par|rec)'));

and you can combine else and if on line 84 into elseif.

Otherwise nice!

Small edit needed

OK