Select
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The Select tool is is a wrapper around LSelect, SSelect, VSelect and Blender's native loop select tool.
It allows you to access all four via a single keymap, which is intedend to be the same as Blender's own loop select keymap, which in turn may varry depending on your key config choice.
Selection
Selection requirements are the same as for LSelect, SSelect and Vselect.
If they aren't met, Blender's native loop select will be called.