Omron “Alps style”
“Alps style” switches are an Omron switch type that are effectively a reduced-size B3G-S switch with only two terminals, that are at least almost compatible physically with Alps SKCL and SKCM switches.
The utility model for the contact assembly—JP H01109148 U—was filed in 1988 and granted in 1989, giving an approximate date of introduction.
This series appears to have lacked alternate action, which is why B3G-S alternate action was used in the NEC 8313-12 keyboard. That keyboard uses linear switches, while the click type was used in some Focus FK-2001 keyboards.