Most often any color wire or color stripe on a white wire is 12VDC POSITIVE. FULL White is 12VDC NEGATIVE or ground....
It is suppose to follow HOUSE WIRING codes but when you mix in the AUTOMOTIVE BATTERY circuits then those two worlds sometimes get mixed together...
Also RV trailers seem to get all kinds of electrical mods by the current owners and does not get installed by professionals... Anything goes there...
I try hard to follow the BLACK for positive 12VDC and WHITE for negative 12VDC installs. Then you go buy a brand new replacement JENSEN AM/FM RADIO and right out of the box it has RED WIREs for POSITIVE 12VDC and BLACK for NEGATIVE 12VDC ground. SO you end up with a RED WIRE on TOP of a BLACK wire on a wire terminal somewhere haha... Makes the 'old timers' turn over in their graves...
Keeping a good multimeter around is very handy with the RV TRAILERS...
Roy Ken