Adds alternative source expression.
            
Namespace: CMS.MacroEngineAssembly: CMS.MacroEngine (in CMS.MacroEngine.dll) Version: 8.0.0.0 (8.1.5347.20411)
Parameters
- source
 - Type: 
System String
Source for which the alternative expression should be created 
- expression
 - Type: 
System String
Expression which will be evaluated if the source is not found in base data sources 
See Also