Those (NPPQ_, NPQB_...) are "timelined" unit.
If you try them into museum, you will see a lot of details changing during different years (hull colors and details, lighted\darkened windows, platforms for guns etc).
Idea behind this is to have units who can "change" during war's years without adding clones and clones (Queen of Bermuda is a lighted cruise ship until september '39, become darkened during conversion days, become an AMC with guns, a scout planes, different windows configuration, different lifeboats configuration, gray colors etc, and late in the war she become a troop transport, without hangar\scout planes, different masts configurations, cranes, etc. (see the proposed picture near to dowload link).
Hull included in dat file is just a reference for place guns' nodes.
For see all pieces togheter, you can export single .obj files in 3ditor from library and import them into main dat under related nodes, following .eqp definitions.
This will require time
Best regards,
Vd