The Digital Tradition and the Mudcat Songbook aren't the same thing, Fidele - the DT is made up of songs out there in the wild, traditional or not-so-traditional, and you get to it by clicking on the Digi-Trad search button up top - and if you know a song that you think ought to be there but isn't (remembering that song titles aren't the way to find a song, since they vary so much), you post it as a new thread with the prefix Lyr Add, and in time it'll get picked up and included. Or not, depending.

The Mudcat Songbook is made up of songs written by Mudcatters who are agreeable to having them included. And you get to that via the Quick Links button.