Returns True if the specified property for the specified node has a defined (overridden) value. Returns False if the node or property is not found.
IsDefinedPropVal(PropAbbrev:String,Node:String):Boolean
PropAbbrev is the name of the property to use.
Node is the name of the node to use.
IsDefinedPropVal(Custom.AccountType,Abbrev())
Returns True if the Account Type property has a defined (overridden) value.