What was this DIG (or may be D G ) Interface on IDE (PATA) CD Writer?

I hope this question is in scope for this site.

While I was just about to throw away my very old internal CD Writer (PATA Interface) in E-Waste, I saw two pins on its extreme left back panel interface mentioning DIG ( D G being Pinouts) on it.

See the snapshot, the next one right to it is a 4 Pin Audio interface and next to that is Master/Slave/Cable Select pins.

Does anyone know what was this DIG? There’s absolutely no reference of it on the internet.

It is digital out. The digital auto out has both channels encoded and passed along one wire pair.

Not sure why it is labeled D/G--perhaps so you don't think you can connect it to an analog receiver--but it is signal and ground. The analog audio connector requires a pair for each channel, and it is labeled Right, Ground, Ground, Left. In reality, most analog audio connectors I have seen use a shared wire for ground so the connectors usually only have 3 wires.

Digital Out. This is how it's labeled on my CD writer:

Google "cd spdif 2-pin" and you'll find suitable cables.

Digital audio output for connecting to a sound card. Back in the day it (or the analogue equivalent) was required to play CD audio through computer speakers