Time index on ATC audio tapes
A question arose about time index marking of ATC audio, how it is recorded, etc, these days.
In my day it was a multi-channel reel-to-reel tape and if there was an incident we'd call 'Mark tape!" and a slip of paper was inserted into the reel.
What about these days? Do they use tape or is it all to digital hard drive? Do they have time index marks tied to the audio?
Thanks in advance.