When on, you can edit vértices without affecting the object's UV
mapping. You can choose which mapping channels to preserve
; see Preserve
UVs Settings, following. Default=off.
UVs, there is always a direct correspondence between an object's geometry and its UV
mapping. If you map an object, and then move vértices, the texture moves along with the sub-objects, whether you want it to or not. If you turn on Preserve
UVs, you can perform minor editing tasks without changing the mapping.
Tip: For best results with Preserve
UVs, use it for limited vertex editing. For example, you'll usually have no trouble moving a vertex within edge or face constraints. Also, it's better to perform one big move than several smaller moves, as múltiple small moves can begin to distort the mapping. If, however, you need to perform extensive geometry editing while preserving
mapping, use the Channel Info utility