Are lookups in mod_rewrite's maps cached for the request?

[Mikhail T.]

Suppose I have the following construct:

   ...
   RewriteCond    ${mymap:%1|NOT_FOUND}    !=NOT_FOUND
   # Store the lookup-result in environment variable "target":
   RewriteRule    -    -    [DP,E=target:${mymap:%1|NOT_FOUND}]
Note, that the key for lookup in map mymap is the same. How many map-lookups 
will mod_rewrite perform? I'm hoping, only one...

Now, I know, that there are "maps" and "fastmaps" -- the latter caching the 
lookup-results for ever. My question is about regular maps -- do they and, if 
not, should not they, cache the lookup results for the duration of a request?

Thanks! Yours,

   -mi