Hi Erwin ,
Thanks a lot for your answer.
This is exactly the ambiguity I have : Me as a developer I don't know what to generate(in UVM model) exactly when this field is true/false.
Actually UVM provides some built-in tests (register access, reset test , bit bash test, ...), and provides some variables (i.e NO_REG_TESTS) to disable these tests for a given register.
So my interpretation was to use "testable" field to disable these UVM tests, but I still have some doubts it is not the good interpretation.
I am wondering if this ipxact field is related also to other things