Prooflistening OK that's what DPL means: Dedicated Prooflistener, which is the volunteer who will prooflisten (PL) all sections in a project.
You will get to know the jargon quite fast here.
A few more that might be interesting:
MW - the Magic Window you see in each first post, where all the sections are listed
MC - Meta Coordinator, the admin doing all the background work on a project including cataloguing
BC - Book Coordinator, any volunteer who offers to run a project, either a solo or a group project who is in charge of the MW and assigning sections and welcoming volunteers
So in this project for example, I was MC, BC and DPL. That can happen, but very often these three jobs are done by three different volunteers.
Sonia