Digital audio questions

[Donald L. Roberts]

I have two small television sets, each of which has what looks like an R 
C A jack which is labeled as some sort of audio output.  Since it is not 
analog, just what type of digital audio is it likely to be?

On a similar note, what type of digital audio do my mini disc players 
use?  I know that the recording format is a-track, but is the digital 
audio sdif or something else?

Thanks for answers.

Don Roberts