ObjectProperty vs AnnotationProperty ?

[psiotwo]

Some properties are marked as AnnotationProperty, although they apparently point an Orphaned classes, e.g.:
C016, C017, C020, C021, C022, C025, C026, C027.

This might be completely justified, just would like to know, what is the rationale behind this split - which properties are object properties and which are annotation properties? In other words what type of OWL reasoning do you perform to justify this split?