3.11 Entity Tags
13.3.2 Entity Tag Cache Validators
I'am not sure if it's good or bad also how helpfull it really is, maybe
someone on the list could help to understand this ;-)?!
I saw that browsers and cache proxies use Last-Modified as tag but not as
time value. If they want to revalidate response, they send If-Modified-Since
with the same value as they have received. MSIE adds ", length=XXXX" string.
nginx gets time in seconds from IMS header and does IMS == LM comparsion,
but not "IMS <= LM" comparsion to return 304.
Btw.: How is the entity value calculated?!
Now Apache use "FileETag INode MTime Size" directive. Before Apache 1.3.23
the ETag was always formed as "inode-size-mtime" and the same files
from mirror image servers have the different ETags.