Yes, Layer States...
Also, even within Civil Drawings we try to minimize any duplication of information (notes, or details)
This is to reduce the chance that any not or detail is revised, and a duplicate note or detail is NOT also edited
leading to either confusion or construction errors.
I know I've said this maybe too many times, however unless there is an absolute need to annotate an object that is the exact mirror
or exactly symmetrical on a part or assembly it is conventional to omit.