What's the meaning of "(?i)" in Lighttpd rewrite rule?

#1

This article : https://www.cyberciti.biz/tips/lighttpd-mod_rewrite-redirect-hotlink-image.html mentions :

$HTTP["referer"] =~ ".*BADDOMAIN\.com.*|.*IMAGESUCKERDOMAIN\.com.*|.*blogspot\.com.*" {
    url.rewrite = ("(?i)(/.*\.(jpe?g|png))$" => "/hotlink.png" )
}

in the “url.rewrite” line, I understand the “change THIS into THAT” structure, but what exactly does the “(?i)” leading the regular expression matching image files mean ?

I know Lighttpd has some specific regular expression syntaxes but can’t find this one in the documentation. I guess this could toggle a case-insensitive search…

Can anybody confirm / provide further details / point to the corresponding documentation ?

Thanks

#2

yes, it is a case insensitive match.