code: private static boolean processPositionalVariation(CharIter iter, CxSmilesState state) {
          if (state.positionVar == null)
              state.positionVar = new TreeMap<>();
          while (iter.hasNext()) {
              if (isDigit(iter.curr())) {
                  final int beg = processUnsignedInt(iter);
                  if (!iter.nextIf(':'))
                      return false;
                  List<Integer> endpoints = new ArrayList<>(6);
                  if (!processIntList(iter, DOT_SEPARATOR, endpoints))
                      return false;
                  iter.nextIf(',');
                  state.positionVar.put(beg, endpoints);
              } else {
                  return true;
              }
          }
          return false;
      }
docs: Positional variation/multi centre bonding. Describe as a begin atom and one or more end points.
  
  @param iter input characters, iterator is progressed by this method
  @param state output CXSMILES state
  @return parse was a success (or not)