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[1] [CITE@en[mod_rewrite - Apache HTTP Server Version 2.5]]
([TIME[2017-08-18 17:24:45 +09:00]])
<https://httpd.apache.org/docs/trunk/mod/mod_rewrite.html#RewriteCond>
]FIGCAPTION]

> IS_SUBREQ
> Will contain the text "true" if the request currently being processed is a sub-request, "false" otherwise. Sub-requests may be generated by modules that need to resolve additional files or URIs in order to complete their tasks.

]FIG]