weak entity tags vs Apache moddav

Hi.

In section 3.11 [1], RFC2616 states:

"A "weak entity tag," indicated by the "W/" prefix, MAY be shared by two
entities of a resource only if the entities are equivalent and could be
substituted for each other with no significant change in semantics. A weak
entity tag can only be used for weak comparison."

In 13.3.3 [2], it gives the following example:

"An entity's modification time, if represented with one-second resolution,
could be a weak validator, since it is possible that the resource might be
modified twice during a single second."

Apache moddav indeed returns weak entity tags based on a filesystem
timestamp. However, as far as I understand there's no guarantee whatsoever
that two entities written within one second indeed can "be substituted for
each other with no significant change in semantics". So is this a bug or am
I missing something important?

Julian


[1] <http://greenbytes.de/tech/webdav/rfc2616.html#rfc.section.3.11>
[2] <http://greenbytes.de/tech/webdav/rfc2616.html#rfc.section.13.3.3>

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