If you are in automotive, TS 16949 tells you to use your customers critical characteristic symbols. Ford, GM & Chrysler all have their own symbols. We supply OE to a couple of other customers and they have their own as well. For products that don't have an OE customer, we have our own symbols. We use 3, one for safety & regulatory characteristics, one for critical fit & function and a 3rd if SPC is required. In all cases, we have the symbol defined and I use an offset attachment so it stays with a dimension or GD&T. I redefined the surface finish symbol to include an optional safety symbol as we have a lot of sealing surfaces that could leak fuel.