E.g. sheeps of the enemy should not appear in FOW nor on the minimap
https://github.com/0ad/0ad/blob/master/binaries/data/mods/public/simulation/templates/template_unit_fauna.xml has it 'RetainInFog` set to true.
https://github.com/0ad/0ad/blob/6a43d8528e444c7f745227105983718159a3558b/binaries/data/mods/public/simulation/templates/template_unit.xml#L122 has it set to false.