It does get confusing when people invent their own. We've had people using DN for "dear neighbour" and everybody in the thread thought they meant "dear niece" and DF has meant "dear friend" and "dear father". And does GP stand for GrandParent(s) or GP the doctor?
As a trained secretary I find that stopping to engage shift lock and writing random capitals stops the flow of typing, although I sometimes use them on my tablet.
To find the link people have given above, switch to "desktop site" if you're not already, and it is listed at the top of the page. You can switch from desktop to mobile site by scrolling right to the bottom of the page and clicking on the relevant word in small print.
And well done for calling them abbreviations. To my mind, an an acronym is an abbreviation that spells a pronounceable word; DGS, DGD, etc. are definitely not pronounceable words in English!