For us 3d life forms it is easy to determine were our left and right sides are as we only have symmetry across a line so we cannot rotate our right and left sides around any circle of Symmetry. We always know were our right and our left is.

A tetronian though would have a circle of symmetry though. Et/It's Left Kata, Left Ana, Right Kata, and Right Ana sides would all look the same and could all rotate around the circle of symmetry. If you choose to look at one side of a tetronian and then saw that tetronian later on you wouldn't know, which side you looked at. So basically unless for a tetronian each of et/it's sides had unique characteristics that were only found on that side which side et/it would define as et/it's Left Kata, Left Ana, Right Kata, and Right Ana would be somewhat arbitrary. Once a tetronian decided that one side was to be et/it's Right Kata for instance et/it could then define each of et/it's other sides but if a tetronian looked at anyone of et/it's sides if et/it didn't have a side that et/it used to define the other sides et/it would not know, which side et/it is.