* CGI における定義

[1] 
[PRE(ABNF code)[
      separator     = "(" | ")" | "<" | ">" | "@" | "," | ";" | ":" |
                      "\" | <"> | "/" | "[" | "]" | "?" | "=" | "{" |
                      "}" | SP | HT
      CHAR          = alpha | digit | separator | "!" | "#" | "$" |
                      "%" | "&" | "'" | "*" | "+" | "-" | "." | "`" |
                      "^" | "_" | "{" | "|" | "}" | "~" | [[CTL]]
]PRE]

[5] [[CGI]] としては[[文字コード]]は[[システム定義]]とされていますが、
[[Unix]] では [[US-ASCII]] になっています [SRC[>>4]]。

** 仕様書
[REFS[
- [2] [CITE@en[RFC 3875 - The Common Gateway Interface (CGI) Version 1.1]] 
-- [3] '''<http://tools.ietf.org/html/rfc3875#page-7>'''
-- [4] <http://tools.ietf.org/html/rfc3875#section-7>
]REFS]