non-intersecting elements in `Y` are appended, retaining their partial order.\n  - 'map': `X + Y` performs a merge where the array positions of all keys in `X` are preserved but the values\n    are overwritten by values in `Y` when the key sets of `X` and `Y` intersect. Elements in `Y` with\n    non-intersecting keys are appended, retaining their partial order.\n\nIf `rule` makes use of the `oldSelf` variable it is implicitly a `transition rule`.\n\nBy default, the `oldSelf` variable is the same type as `self`....

extends UA{insert(e,t,r){let n=e.prop==="mask-composite",a;n?a=e.value.split(","):a=e.value.match(Ne.regexp)||[],a=a.map(c=>c.trim()).filter(c=>c);let s=a.length,o;if(s&&(o=this.clone(e),o.value=a.map(c=>Ne.oldValues[c]||c).join(", "),a.includes("intersect")&&(o.value+=", xor"),o.prop=t+"mask-composite"),n)return s?(this.needCascade(e)&&(o.raws.before=this.calcBefore(r,e,t)),e.parent.insertBefore(e,o)):void 0;let u=this.clone(e);return u.prop=t+u.prop,s&&(u.value=u.value.replace(Ne.regexp,"")),thi...

            "type": "string"
          },
          "message": {