Instance Identifier is unable to represent Choice / Case, only children

It is impossible to construct instance identifier, which will explicitly reference choice / case. This makes binding instance identifier not suffiecient expresive,
since it is impossible to uniquelly reference nodes in following situation:

Module 1:
grouping foo {
container bar {

}
}

choice bar {
case foo

{ uses foo; }

}

Module 2

augment bar {
case foo2

{ uses foo; }

}