From language/typesystem

See Original text in context

Marks a List method to indicate to hyperoperator to not descend into inner Iterables to call this method. This trait generally isn't something end users would be using, unless they're subclassing or augmenting core List type.

In order to demonstrate the difference consider the following examples, the first using a method (elems) that is nodal and the second using a method (Int) which is not nodal.

say ((1.0, "2", 3e0), [^4], '5')».elems; # OUTPUT: «(3, 4, 1)␤» 
say ((1.0, "2", 3e0), [^4], '5')».Int    # OUTPUT: «((1 2 3) [0 1 2 3] 5)␤»