The question of required elements has come up in
discussion here. Specifically, among the top-level
19 elements (title, name, type of resource, etc.)
none is mandatory. Nor do we propose that any
among these be mandatory, but that leaves the
possibility of empty records. An easy way out is
to add the rule that "at least one of these 15
elements must occur". That would prevent empty
But maybe it's reasonable to consider a rule like
"at least one of 'title' and 'identifier' must
occur". Is this a reasonable rule?
While we don't think that 'title' (itself) should
be mandatory, and neither do we think 'identifier'
should (although we do recognize it is appropriate
for an institution to develop metadata policies
that might specify either of these as mandatory)
if a record has neither title nor identifier, can
it really identify anything?