Edit > Select > By Crease Angle selects all contiguous polygons that meet at a specified angle (or less), starting from a single polygon, a cluster of polygons, or multiple singles or clusters. Select one or more seed polygons before or after clicking Edit > Select > By Crease Angle.
The parameter is:
Angle field - specifies the joint angle between two polygons in order for an existing selection to be extended from one to the other.
OK button - closes the dialog with the selection extended per the Angle field.
Cancel button - closes the dialog and restores the selection to be the same as when the function started.
Crease Angle Mode
is a mode of operation
in which a selection is expanded to include all contiguous polygons that
meet at a specified angle (configured at Tools > Options) or less,
starting from a single polygon, a cluster of polygons, or multiple singles
or clusters. Select one or more seed polygons before or
after activating Crease Angle Mode.