Today i was trying to find out what could be the different values for it.
So i had my custom workflow activity registered against all the triggering conditions.
i.e. Record is created, record status changes, record is assigned, record attribute change and record is deleted.
Well these were my findings
for record is created the message name was “Create”
for record status changes, record is assigned, record attribute change it was “Update”.
for record is deleted it was “Delete”.
And one more thing if we have selected both the conditions i.e. record attribute change and record is assigned, owner field within record attribute change gets auto selected.