# What are early/inside and late/outside turns (see, e.g., PBN Manual Order 8260.58A) and when do pilots perform them?

While studying FAA's PBN Manual (Order 8260.58A), I came across the concept of early/inside and late/outside turn construction (Section 5-3. Turning Departures).

For each of the possible cases, it provides instructions for constructing different Obstacle Clearance Areas.

Here are some examples:

a.) Early and inside turn construction

1. Turn following VA leg.

3. Turn-at-fix (FO or FB).

b.) Late and outside turn construction

1. Wind spiral application

My question is, what are these kind of turns exactly? Are they special cases of a "normal" (expected) turn? In addition, how do pilots know when they have to perform such turns?

What also confuses me is the fact that the PBN manual, which describes the design of IFPs, covers such cases that have to do with a pilot's/ATC's "on the spot" decision. When designing, for example, a SID, shouldn't you end up with one (multi-branched or not) Departure Procedure, with specific waypoints selected after the evaluation of specific Obstacle Clearance Areas covering "normal" turns and not special cases?