Default (verb) - Generalness (eg. I play the piano)
Common Present (verb-eht) - Observed action in the present (eg. I [am] eat[ing] cake)
Common Past (verb-oht) - Observed action in the past (eg. I [have] 
Common Future (verb-aht) - Assumed Action in the future
Command (verb-elet) - Command (eg. Eat cake you! (note the trashy word order change in this 'English' example))