MO - morning.
NO(like NI) - night.

This is a patch design for a hiking club from the Estonian Youth Work Department (MONO). 

Patches can be attached to Velcro panels on clothes, equipment and backpacks. The patches can be worn upside at day or upside down at nigh. It is possible to divide this way people into 2 teams for e.x. for a game.

The star and moon display the letter "i". Where the base is the crescent and the dot is the star Aldebaran.