From quine's wiki

Main: RegExpApplet

See Regular Expressions for more information.

Sun's JavaDoc for java.util.regex.Pattern[1]

Sun's Guide To Regular Expressions in Java

Another Regex Guide

Regular Expressions: Don't Overuse Them (@ Coding Horror)

Embedded flag expressions can be used at the beginning of the pattern. The following notes have been collated from Sun's JavaDoc[1].

• (?i) case insensitive
• (?m) multiline mode
  • By default, the regular expressions ^ and $ ignore line terminators and only match at the beginning and the end, respectively, of the entire input sequence. If MULTILINE mode is activated then ^ matches at the beginning of input and after any line terminator except at the end of input. When in MULTILINE mode $ matches just before a line terminator or the end of the input sequence.
• (?s) dotall mode
  • In dotall mode, the expression . matches any character, including a line terminator. By default this expression does not match line terminators.
  • (The s is a mnemonic for "single-line" mode, which is what this is called in Perl.)
• (?u) unicode case
  • Enables Unicode-aware case folding.
  • When this flag is specified then case-insensitive matching, when enabled by the CASE_INSENSITIVE flag, is done in a manner consistent with the Unicode Standard. By default, case-insensitive matching assumes that only characters in the US-ASCII charset are being matched.
  • Specifying this flag may impose a performance penalty.