Use the ADD directive to add value to the
 Access Point attribute if it does not already have one.

 Syntax:

 ADD DSA SUPERIOR REFERENCE <attr> {<value>}

 where <attr> is the name of the Characteristic
 attribute and <value> is the value you want to add to
 the attribute. Note that the Access Point attribute
 is single-valued, so you can only use the ADD directive
 if the Access Point currently has no value.