anchor.diff:  should form a globally-unique identifier for a dataset. In the TDS, it
   is especially important to add the `ID` attribute to your datasets.
   
  +[source,xml]
   -----------------------------------------------------------------------------------------
   <service name="odap" serviceType="OpenDAP" base="/thredds/dodsC/"/>
   
  
positive.code: When a catalog includes multiple datasets, it can often be the case that
  they have share properties. For example:
  
  ---------------------------------------------------------------------------------------------------------------------------------------------------
  <service name="odap" serviceType="OpenDAP" base="/thredds/dodsC/"/>
  
  
negative.code: 
  1.  Find the service referenced by the dataset:
  +
  [source,xml]
  ----------------------------------------------------------------------------------------------------------
  <service name="odap" serviceType="OpenDAP" base="/thredds/dodsC/" />
  <dataset name="SAGE III Ozone 2006-10-31" serviceName="odap" urlPath="sage/20061031.nc" ID="20061031.nc"/>
  