The syntax for using an object class property variable in an expression is
#ObjectClassName.Category.Property
For example, to retrieve the values in the Diameter field of the Pipes table in the PipeRun object class, enter #Piperun.OD:Pipes.Diameter. To retrieve the values in the layer property, which is in the General category, enter #Piperun.General.Layer. To retrieve the values of the end node of the LocalRoads topology in the Roads object class, enter #Road.Topo:LocalRoads."end node". Use quotation marks so the space in the name "end node" is interpreted correctly as part of the property name.