Re: etag in untagged production of If header

My interpretation of the No-tag-list production in an If header is that is is
used for those cases where the condition (a list of state tokens and/or e-tags)
applies to the (single) target resource of the request method, no other
resource is effected. The Tagged-list production is for methods that effect
more than one resource and therefore need to provide matching conditions for
each.