This technology is multi-fauceted. It is not only related to musical instrument manufacturers and music software developers (Technology Side), but also related to music publishers and music educators (Education Side), all over the world.
Let's take a look at a typical scenario. You have a MIDI keyboard equipped with DoReMi+. Here comes a musical instrument manufacturer. This is a stand alone configuration and works just fine. Now, what's typically happens is that you want to use DoReMi+ while reading music with your notation program on your PC. Here comes a music software developer.
If you go to school, you study under a teacher who teachs Do Re Mi. Here comes a music educator. He/she uses a book with DoReMi+. Here comes a music publicher.
This whole ecosystem is created to make music learning more effective and fun.
The simplest implementation utilizing standard MIDI wave table based synthesizer (Hardware/Software) covers the standard 88 piano keys with Do Re Mi (aka Solfege) note identifications for one MIDI channel.
It supports both Fixed Do and movable Do Systems. The setting can be changed locally with hardware or software switches or remotely through special MIDI commands.
More elaborated implementations can be performed with more MIDI channels and/or a full customization.