Regular Expression Patterns
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  a     Any ordinary character (not mentioned below) matches that character.

  \     The backslash quotes any character.  "\$" matches a dollar-sign.
        n, t, r, f mean newline, tab, return, and form_feed respectively.

  ^     A circumflex at the beginning of an expression matches the
        beginning of a line.

  $     A dollar-sign at the end of an expression matches the end of a line
        including newline.

  *     An asterisk matches zero or more of any character.

  ?     A question mark matches any single character except a new_line.

  :a    A colon matches a class of characters described by the following
  :d    character. 'a' - alpha, 'd' - decimal (0-9), 'n' - alphanumeric
  :n    'w' - white space (matches spaces, tabs, and control chars.
  :w

  @     An expression followed by an at sign matches zero or more
        occurrances of that expression: "fo@" matches "f", "fo",
        "foo", etc.

  +     An expression followed by a plus sign matches one or more
        occurrances of that expression: "fo+" matches "fo", etc.

  -     An expression followed by a minus sign optionally matches
        the expression (expression can be there or not).

  []    A string enclosed in square brackets matches ANY character in
  [~]   that string, but no others.  If the first character in the
        string is a ~, the expression matches any character NOT in the
        string.  For example, "[xyz]" matches "xx" and "zyx", while
        "[~xyz]" matches "abc" but not "axb".  A range of characters
        may be specified by two characters separated by "-".  Note
        that [a-z] matches alphabetics, while [z-a] never matches.

  .ñd   A dot (.) followed by a + or - 1 to 9 causes the cursor to position
        to that offset from the start of pattern.

  .c    A dot (.) followed by other than a + or - causes the cursor to
        position to that character after the start of pattern.  If the
        character is not found subsequent to the start of the pattern,
        the cursor is placed on the first character of the pattern.
        The dot operator may appear anywhere in the search pattern
        except in [] where it would be taken literally.  A dot by
        itself means position cursor to end of pattern.