You can use data model objects in expressions, like time levels, dimension columns, and fact columns.
To reference a data model object, use the syntax:
Fact/Dimension Table Name"."
"Order Metrics"."Booked Amount"-"Order Metrics"."Fulfilled Amount"
The Expression Elements section includes only items that are relevant for your task, so not all fact tables and dimension tables might be listed. Similarly, time hierarchies are included only if the Time fact table is joined to the current table.