The term Blade shape is used to refer to the geometrical outer shape of a Blade aerodynamical station. In Ashes we make a distinction between two types of blade shapes:

Airfoil shapes, for which a unique chordline can be defined from the leading edge to the trailing edge. For such a shape, an angle of attack can be defined as the angle between the relative wind velocity and the chordline
Circular shapes, which are defined as circles and are typically used for the part of the blade that it closest to the hub for structural reasons. For these shapes, a unique chordline cannot be defined, and therefore it does not make sense to define an angle of attack

It is important to note the distinction between these two shapes when analysing data from the Blade [Span] sensor, As different Fields are given at different numbers of blade shapes.