Earlier quoted context omitted.
Ok, my only other guess was digital audio cable. TLAs (three letter acronyms) are hard.
In the network world context it's quite obvious and I guess that is what it is written for. For those not in that context I guess it's quite understandably confusing.
Tangentially… you could build a SFP module that uses a digital to analog converter, outputting the data as a range of voltages vs 1/0s. Hook it up to a speaker for terrible audio. Then listen to it with a microphone hooked up to an Analog to digital converter sfp module on the other end!