Pioneer has 'SR' - system remote
Onkyo had 'RI' - remote integration now called remote interactive
Sony had 'R' - remote
There were others.
Much of the Yamaha early RS was done with one receiver and multipin plug ribbon cables of different sizes for different pieces of gear linking them up. I've got a boxful someplace because many receivers/amps came with up to three or four in the box. As time went on, they just put an IR receiver in most pieces of gear further up the range and either shipped it with a remote or charged extra for one if you wanted say, a cassette deck remote.