With angle sections the rectangular axes and member axes are always located by the reference node/axis but you have the choice of using either rectangular axis properties or principal axis properties. This choice is made when you select the section from the steel section library. Transverse member loads are always referred to the member y and z axes (rectangular).
When you choose rectangular axis properties they are used as if they were principal axis properties and results are referred to the member y and z axes (rectangular). This choice is appropriate when bending is not significant or the section is assumed to be constrained to bend about a rectangular axis.
When principal axis properties are used the member principal axes are rotated from the member y and z axes and results are referred to these (rotated) axes. Choose principal axis properties for angles that are free to bend about the principal axes.
Microstran design always performs design calculations for angles with reference to principal axes. If analysis results are referred to rectangular axes they are resolved into principal axis components for design. Steel design restraints act in principal axis directions as shown below.
STEEL DESIGN RESTRAINTS FOR ANGLE