// DSTU2: tags
 //public void Collect(Tag tag)
 //{
 //    string scheme = Assigned(tag.Scheme) ? tag.Scheme.ToString() : null;
 //    string term = tag.Term;
 //    string label = tag.Label;
 //    //string tagstring = glue("/", scheme, term);
 //    BsonDocument value = new BsonDocument()
 //        {
 //            { "scheme", scheme },
 //            { "term", term },
 //            { "label", label }
 //        };
 //    Write(InternalField.TAG, value);
 //}
 public void Write(Definition definition, Quantity quantity)
 {
     switch (definition.ParamType)
     {
         case Conformance.SearchParamType.Quantity:
         {
             BsonDocument block = quantity.ToBson();
             document.Write(definition.ParamName, block);
             break;
         }
         case Conformance.SearchParamType.Date:
         {
             break;
         }
         default: return;
     }
 }