How to access standard, i.e. non-custom, properties?

I am trying to get hold of Property values that are NOT Custom Properties

If I define a Customer Property "foo" I can access its value using:

def bar = context.expand('${#Project#foo}')

But how do I access those left-hand standard Properties i.e. those listed on the tabs Project Properties, TestSuite Properties, TestCase Properties, REST TestRequest Properties etc.

Does access to these require some other mechanism?