Transform Orientation

In the Transform orientation pop-over it is possible to select and configure transformation orientations.

Default transform orientations are

Global
Align the transformation axes to world space
Local
Align the transformation axes to the selected objects' local space
Normal
Align the transformation axes to average normal of selected elements
Gimbal
Align each axis to the Euler rotation axis as used for input
View
Align the transformation axes to the window
Cursor
Align the transformation axes to the 3D cursor

With the + a new transformation orientation can be created from the selected object. A name can be specified. It is also possible to remove these custom transform orientations.