code: public static SingleID parseFilterID(String id, int[] pos) {
  
          int start = pos[0];
          Specs specs = parseFilterID(id, pos, true);
          if (specs == null) {
              pos[0] = start;
              return null;
          }
  
          // Assemble return results
          SingleID single = specsToID(specs, FORWARD);
          single.filter = specs.filter;
          return single;
      }
docs: Parse a filter ID, that is, an ID of the general form
  "[f1] s1-t1/v1", with the filters optional, and the variants optional.
  @param id the id to be parsed
  @param pos INPUT-OUTPUT parameter.  On input, the position of
  the first character to parse.  On output, the position after
  the last character parsed.
  @return a SingleID object or null if the parse fails