code: func (st *state) cvQualifiers() Qualifiers {
  	var q Qualifiers
  	for len(st.str) > 0 {
  		if qv, ok := qualifiers[st.str[0]]; ok {
  			q = append([]string{qv}, q...)
  			st.advance(1)
  		} else if len(st.str) > 1 && st.str[:2] == "Dx" {
  			q = append([]string{"transaction_safe"}, q...)
  			st.advance(2)
  		} else {
  			break
  		}
  	}
  	return q
  }
docs: // <CV-qualifiers> ::= [r] [V] [K]