ά character:

In Emacs 23 (Cocoa/NS):

         character: ά (940, #o1654, #x3ac)
preferred charset: greek-iso8859-7
		   (Right-Hand Part of ISO/IEC 8859/7 (Latin/Greek): ISO-IR-126)
        code point: 0x5C
            syntax:
		   w 	which means: word
          category:
		   .:Base, g:Greek, j:Japanese
       buffer code: #xCE #xAC
         file code: ESC #x2C #x46 #x5C
		   (encoded by coding system iso-2022-7bit-unix)
           display:
		   by this font (glyph code)
     nil:-apple-Lucida_Grande-medium-normal-normal-Regular-13-*-*-*-*- 
*-iso10646-1 (#x1AF)

Character code properties: customize what to show
   name: GREEK SMALL LETTER ALPHA WITH TONOS
   old-name: GREEK SMALL LETTER ALPHA TONOS
   general-category: Ll (Letter, Lowercase)
   decomposition: (945 769) ('α' '́')

There are text properties here:
   charset              greek-iso8859-7


In Emacs 23 (Cocoa/NS), with the default font (Monaco):

         character: ά (940, #o1654, #x3ac)
preferred charset: greek-iso8859-7 (Right-Hand Part of ISO/IEC 8859/7  
(Latin/Greek): ISO-IR-126)
        code point: 0x5C
            syntax: w 	which means: word
          category: .:Base, g:Greek, j:Japanese
       buffer code: #xCE #xAC
         file code: ESC #x2C #x46 #x5C (encoded by coding system  
iso-2022-7bit-unix)
           display: by this font (glyph code)
     nil:-apple-Monaco-medium-normal-normal-Regular-12-*-*-*-*-*- 
iso10646-1 (#x00)

Character code properties: customize what to show
   name: GREEK SMALL LETTER ALPHA WITH TONOS
   old-name: GREEK SMALL LETTER ALPHA TONOS
   general-category: Ll (Letter, Lowercase)
   decomposition: (945 769) ('α' '́')

There are text properties here:
   charset              greek-iso8859-7






In Emacs 22 (Carbon):
   character: ά (2908, #o5534, #xb5c, U+03AC)
     charset: greek-iso8859-7 (Right-Hand Part of Latin/Greek Alphabet  
(ISO/IEC 8859-7): ISO-IR-126.)
  code point: #x5C
      syntax: w 	which means: word
    category: g:Greek
buffer code: #x86 #xDC
   file code: ESC #x2C #x46 #x5C (encoded by coding system  
iso-2022-7bit-unix)
     display: by this font (glyph code)
      -apple-lucida grande-medium-r-normal--14-140-72-72-m-140- 
iso10646-1 (#x3AC)