The specifics:
Dive planning: Gas matching, dissimilar tanks, rule of thirds, rock bottom.
Equipment check: Making sure the needed tools and emergency equipment are with the team. Knowing where everything is stowed -- who has it and where.
Line laying: Holding and managing a reel. Selecting sites for primary and secondary ties, and proper technique for putting them in. Running line and putting in ties. Roles of leader (with reel) and second teammate (inspecting and approving ties, adjusting tension and repositioning the knot as required). Situational awareness for everybody: How many ties? What time were they put in? What depth were they at? Which side did we pass them? Keeping the team tight and in communication (passive most of the time, active when necessary). Light signals.
Lights-out exit: Deploying backup lights. Referencing the line. Team positioning and communication. Managing entanglements. Technique for passing ties.
We also discussed technique for handling OOA situations while doing lights-out exits, but we didn't actually practice those.