ifier_ag - qualifier associated with layer-aggregation,
  e.g., _N, _SD</p></li>
<li><p>layer_index - layer index provided, if any</p></li>
<li><p>H_index - H index provided, if any</p></li>
<li><p>V_index - V index provided, if any</p></li>
<li><p>R_index - R index provided, if any</p></li>
<li><p>is_correct_basename - is the parsed basename recognized in
  FP-Standard</p></li>
<li><p>is_pi_provide - is this a PI provided variable e.g., _PI</p></li>
<li><p>is_gapfill - is this a gap-filled variable, _PF_F 