HTTP/2 200 server: nginx content-type: text/plain;charset=UTF-8 content-security-policy: default-src 'self'; connect-src 'self' *.google-analytics.com; img-src 'self' data: www.google-analytics.com www.googletagmanager.com; script-src 'self' 'unsafe-inline' www.google-analytics.com www.googletagmanager.com; style-src 'self'; report-uri /csp-reports content-encoding: gzip accept-ranges: bytes age: 0 date: Wed, 30 Jul 2025 22:12:52 GMT via: 1.1 varnish x-served-by: cache-bom-vanm7210037-BOM x-cache: MISS x-cache-hits: 0 x-timer: S1753913572.060089,VS0,VE871 vary: Accept-Encoding strict-transport-security: max-age=31557600 content-length: 328 =over =item study SCALAR X =item study At this time, C does nothing. This may change in the future. Prior to Perl version 5.16, it would create an inverted index of all characters that occurred in the given SCALAR (or L|perlvar/$_> if unspecified). When matching a pattern, the rarest character from the pattern would be looked up in this index. Rarity was based on some static frequency tables constructed from some C programs and English text. =back