A GedcomX Range.
It will place a Singel date at this.start and this.end,
as well as a Duration at this.duration.
function Range(str) {

  var range = str;

  // If range starts with A, its approximate
  if(range.charAt(0) == 'A') {
    this._approximate = true;
    range = str.substr(1);
  }

  var parts = range.split('/');

  if(parts.length != 2 || (!parts[0] && !parts[1])) {
    throw new Error('Invalid Date Range');
  }

  if(parts[0]) {
    try {
      this.start = new Simple(parts[0]);
    } catch(e) {
      throw new Error(e.message+' in Range Start Date');
    }
  }

  if(parts[1]) {
    if(parts[1].charAt(0) == 'P') {
      if(!this.start) {
        throw new Error('A Range may not end with a duration if missing a start date');
      }
      try {
        this.duration = new Duration(parts[1]);
      } catch(e) {
        throw new Error(e.message+' in Range End Date');
      }
      // Use duration and calculate end date
      this.end = GedUtil.addDuration(this.start, this.duration);
    } else {
      try {
        this.end = new Simple(parts[1]);
      } catch(e) {
        throw new Error(e.message+' in Range End Date');
      }
      if(this.start) {
        this.duration = GedUtil.getDuration(this.start, this.end);
      }
    }
  }

}