File formats? .MID, .KAR, .ST3

[Dave]

Can anyone point me to information on file formats for the following file
types:

.MID, MIDI music file
.KAR, MIDI music file with lyrics annotated for Karaoke
.ST3, another Karaoke file format (similar to .KAR I think)

I am looking for web sites, magazine articles or anything else that has
detailed information about these file formats. Even some commented C code
would be helpful.

TIA,
Dave