It's almost as bad as described in the TheDailyWTF. It's not just bad - it's INCONSISTENT.
>Maybe some of the code is obscurely written, I don't know, but if it's obscure and it works well then that's much better than most hacked up software designed to do boring mainframey work.
And 'hacked up software designed to do boring mainframey work' perfectly describes the general MUMPS code.
We bravely rewrote a few modules of MUMPS code in Erlang with Mnesia database (I love that name - a perfect match for database!) and in less than 10% of original source code. Without even trying.