Battery Disconnect... What does it disconnect??

Have had my trailer for 2 years and have a habit of always turning off the Batt disconnect if it's going to be parked for more than a week or two. Recently I started working on a few lighting upgrades to LED, adding LED strips etc and noticed all the lights still worked with the disconnect off. Checked a few other things... Slides worked, TV worked.... So what exactly does the disconnect actually disconnect? It is in my front compartment and it is definitely wired into something but no idea what. Fully understand there's no way for any of you to give a factual answer without testing, but just curious if there was an RV standard. Now I am plugged in to 110 at home right now so does the AC/DC converter skip the battery even for 12V items? If I was unplugged would most items (12v items) not longer work? Thanks!