TM1 oldschoolers have long been used to being sloppy in our use of language to describe dimensions, hierarchies and rollups. Now that Planning Analytics supports named hierarchies the term "hierarchy" has a specific meaning which we need to respect. Clear and unambiguous communication is important. It may be difficult at first, but if you catch yourself saying “hierarchy” when you really mean “rollup” stop and correct yourself. It doesn’t take long to change the habit and the sooner we all do we can stop second guessing each other.
The colon delimiter used between dimension name and hierarchy name presents a problem when defining PickLists as the same string delimiter is used. But we can overcome this issue by escaping the additional colon character.