> Fullwidth characters are used for backward compatibility with CJK > character > sets, which have a notion of "fullwidth" and "halfwidth" characters. > Fullwidth characters are the same width as individual CJK characters and > fit into a uniform square grid. They should not be used except for > compatibility.
But note that the notion of "fullwidth" (zenkaku) and "halfwidth" (hankaku) in CJK character sets is different from what is called "fullwidth" and "halfwidth" in Unicode. I think for Japanese Katakana you should use the "fullwidth" (in CJK character sets sense) and not the "halfwidth" (in all three senses). There was a nice explanation of this by Asmus Freytag on the CD-ROM which came with Unicode 3.0 E:\TechReports\tr11\index.html This is supposed to be online as http://www.unicode.org/unicode/reports/tr11
