on stomach
Quite simply, when one is lying on one's stomach.
If there's any doubt if the character is lying on their stomach, then a simple benchmark is: If one hip is higher than the other, then the character is on their side and should be tagged with the on_side tag instead.
The following tags are aliased to this tag: on_belly, prone, and lying_on_stomach (learn more).
This tag implicates lying (learn more).
The following tags implicate this tag: the_pose (learn more).