When using the u_where clause in a read trigger of a certain entity, it would be useful to use fields from outside the current entity within the u_where clause. These fields are from an inner entity of the current entity which is also an up entity (or a down entity in case of a 1:1 relation).
When using these fields in the u_where clause, Uniface generates an SQL query which is a join.
When this option is available, there is no need for using discard as a workaround. Discard is bad for performance when using it in this way. Views are also no option, because of the maintainability.