... and so on. I can't think of any advantage to (or excuse for) doing it this way. The only possible reason for it that I can think of, is rather comprehensive ignorance of how XML and related standards work.
The apache module that provides the gateway to Ecometry? That thing was a bear. I can't believe they did all the processing in the apache module rather than with a CGI.
It didn't actually use regular expressions, but parsed the input with a lot of char pointer manipulation.
The reason it worked like this was to have the "XML" tags map directly to the terminal input screens run on the backend, because it essentially input data as if a human was typing it into the terminal and navigating the forms.
I keep meaning to write this up as the worst example of XML abuse I've ever seen; I'm actually surprised someone else here has used the same thing (or even more surprised that more than one party has implemented the same braindead thing).