|Pathologically Eclectic Rubbish Lister|
Wow, MUMPS is a real thing???!! I always thought TheDailyWTF made that up.
Yes, it's old, it's real, and it is still in use. Most implementations are gone, unmaintained or unsupported, but MUMPS is hidden in InterSystems Caché, and you can still write software in MUMPS in a Caché system. Another surviving implementation is GT.M. See also "Current users of MUMPS applications" in MUMPS.
From the 1980s to 2015, a MUMPS implementation was used as the main database for producing and distributing blood products for two federal states (about 5 million people) in Germany. During the 1990s, the system was cloned to support another two federal states for a short time. Duing its last five years, working with that system paid my bills.
That MUMPS system was replaced by a custom application written around a commercial SQL database, originally written in and for a completely different country. Not for performance reasons, but because blood services merged, and a political decision was made to use the larger system. As far as I know, the MUMPS system is still running, disconnected from all other systems, to be able to access the original records that have been ported into the new system.
Update note: A few minutes after posting, I have removed some details that should not have been exposed.
Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)