MuSICA is a MSX music editor released in 1990 by ASCII. Music is entered 
using a Music Macro Language (MML) text which is compiled into the 
binary .BGM files (see https://www.msx.org/wiki/MuSICA). 

It seems that due to RAM limitations songs were sometimes split
into an "intro" and a "loop" part. (A "'" is sometimes used
in filename to mark the intro file, and a "-" for the loop file).

The format does not contain any of the meta informtion that 
would usually have been available in the original MML file. 


note: "-unknown/NVmag" contains a quite a few unidentified
songs but the folder name suggests that these files all originated
from some "NV magazine". The "RS3" filename prefixes in the same folder
remind me of other files that I came across on "ECHIKUSO 5 + 6" 
disks (this is a series of 1-8 of which I only found 5 and 6).