See `8.11.2.2 Optional Content Membership Dictionaries` -> `VE` entry. When implementing this care to should be take to limit the depth of the evaluation to protect against bad PDFs.
cae OPS.etFllClrSpace:
        cae OPS.etStrkeClr:
        cae OPS.etStrkeClrN:
        cae OPS.etFllClr:
        cae OPS.etFllClrN:
        cae OPS.etStrkeGray:
        cae OPS.etFllGray:
        cae OPS.etStrkeRGBClr:
        cae OPS.etFllRGBClr:
        cae OPS.etStrkeCMYKClr:
        cae OPS.etFllCMYKClr:
        cae OPS.hadngFll:
        cae OPS.etRenderngIntent:
          peratrLt.fnArray.plce(, 1);
          peratrLt.argArray.plce(, 1);
          --;
          cntnue;
        cae OPS.etGState:
          cnt [gStateObj] = peratrLt.argArray[];
          let j = 0,
            jj = gStateObj.length;
          whle (j < jj) {
            cnt [gStateKey] = gStateObj[j];
            wtch (gStateKey) {
              cae "TR":
              cae "TR2":
              cae "HT":
              cae "BG":
              cae "BG2":
              cae "UCR":