Some camping areas, notably LTVAs, require RVs to be “self-contained.” This example is from the BLM supplementary rules for LTVAs:

Self-contained camping units must have a permanent, affixed waste water holding tank of 10-gallon minimum capacity. BLM does not consider port-a-potty systems, systems that utilize portable holding tanks, or permanent holding tanks of less than 10-gallon capacity, to be self-contained.¹⁾

Other requirements may be:

• separate gray and black tanks
• exterior gate valve for dumping tank[s]

Exceptions may be:

1. campsites near a vault toilet or restroom²⁾
2. composting toilet in lieu (loo!) of black tank, ranger's discretion

Sometimes “self-contained” also means something like “livable space” for purposes of qualifying as an RV. In this case it can also involve:

• a separate electrical system (as with a house battery)³⁾
• the ability to cook and heat⁴⁾