Previous empty submission checks required the submission to
be saved to the database. This patch adds a new method to
submission plugins that lets them report whether the submission
is empty before it is saved.
New events have been created for submission plugins. This is
part of the consistancy move by adding the same type of event through
all of the modules.
AMOS BEGIN
MOV [event_submission_updated,mod_assign],[eventsubmissionupdated,mod_assign]
AMOS END
