^   beginning of line 
      if ^ is the first character in the pattern
     Sample: ^subj:    line start with 'subj:'

$   end of line 
    if $ is the last character in the pattern.  
    The result doesn't contain return code. 
     To contain return code, specify '\r' instead.
     Sample:  ^$    blank line (without return code)
     Sample:  ^\r   blank line (with return code)

.    any character 
     Sample: a.d 
     Start with 'a' and follwed by any character and
     end with 'd'.  It matches in 'and', 'add', 'dandy'.

*   zero or more specified patterns
     Sample:    an*d
     Start with 'a' and follewed by zero or more 'n's
     and end with 'd'.  It matches in 'and', 'advance', 
     'add'.
     
+   one or more specified patterns
     Sample:    an+d
     Start with 'a' and follewed by one or more 'n's
     and end with 'd'.  It matches  'and', 'annd' but
     not in  'advance', 'add'.

?   zero or one specified pattern
     Sample:    an?d
     Start with 'a' and follewed by zero or one 'n'
     and end with 'd'.  It matches  'and', 'add' but
     not  'annd'.

\   escape
     Use escape pairs when you want to express
     characters that has special meanig in regular
     expression such as '^', '$', '\'.
     Sample:   \^   character '^' as data
     Sample:   \\   character '\' as data
     Sample:   \$   character '$' as data
     Sample:   \*   character '*' as data
     Sample:   \+   character '+' as data

     Use escape pairs to express none-printing
     characters as follows.
     '\t' =TAB, '\r' =CR, '\n' =LF, 
     '\s' =SPACE, '\b' =BS
     
     To express characters as hex-decimal codes,
     use '\h' follewed by its hex-decimal codes.
     Sample:   \h20        space (one byte)
     Sample:   \h8140   two bytes kanji space
     
[ ]  character class
     Set and range pattens matches some characters.
     You can use also 2byte characters as its components.
     Use '-' to express  the range pattern. 
     Use '^' to express the exception set.
     Sample:   [abc]    any one of characters a, b, c.   
     Sample:   [A-Z]   any one of characters in the range
                                   A to Z, capital alphabets.
     Sample:  [^a-z]  any one of characters  except small
                                   alphabets. 
     Sample:  [a-xABC] 
                                  any one of characters in the range a 
                                  to x or characters A, B, C.
     Sample:  [\t\s\h8140]+$
                                  one more continuous characters of 
                                  tab, space or kanji space at the end 
                                  of line.

{}   group
      Use {} to divide find strings into desired groups that
      are used in replacement strings.
      
      For example, person name is expressed as follows.
      
      {[A-Z][a-z]+}\s+{[A-Z][a-z]+}

       First group {[A-Z][a-z]+} is given name.
       Second group {[A-Z][a-z]+} is family name.

      First group is expressed as \1 in replacement string,
      second group is \2. 

      To replace names to family name first styles, specify 
      follwoing replacement string.
      
      \2, \1
      
      Family name is first, follewed by comma and given
      name.