Hello Joseph,
Catalog Query has a parameter called "SelectedObjects" which can take in tag names dynamically. For example, if you are running the query through a URL, then your parameter would look similar to
SelectedObjects = CatalogConnector.Root.ProductionUnit.EquipmentTag1, CatalogConnector.Root.ProductionUnit.EquipmentTag2,..
The tag names are passed are comma (,) seperated values.
However, in BOBJ, the parameters ObjectName.xx is merely a place holder for the UI. If the BOBJ connector has to pass tags dynamically, then it might as well be using the same SelectedObjects parameter to pass the input.
I am not sure about retrieve properties.
According to me,
The retrieve properties mode in catalog query, will only query the value of the properties. You would anyways have to pass the property names to the query.
Rohit Negi any thoughts 
?
Regards
Tufale Ashai