cdm/src/main/java/ucar/nc2/util/rc/RC.java
static synchronized public void
  add(String key, String value, String url) {
    if (key == null) return;
    if (!initialized) RC.initialize();
    Triple t = new Triple(key, value, url);
    dfaltRC.insert(t);
    // recompute well-knowns
    setWellKnown();
  }
static synchronized public void
  add(String key, String value, String url) {
    if (key == null) return;
    if (!initialized) RC.initialize();
    Triple t = new Triple(key, value, url);
    dfaltRC.insert(t);
    // recompute well-knowns
    setWellKnown();
  }
Allow users to add to the default rc

@param key
@param value
@param url   null => not url specific