- and Internet-oriented date and time
formats.</li>
<li>Alphabetic time zone abbreviations should not be used as unique
identifiers for <abbr>UT</abbr> offsets as they are ambiguous in
practice. For example, in English-speaking North America
“<abbr>CST</abbr>” denotes 6 hours behind <abbr>UT</abbr>,
but in China it denotes 8 hours ahead of <abbr>UT</abbr>,
and French-speaking North Americans prefer
“<abbr title="Heure Normale du Centre">HNC</abbr>” to
“<abbr>CST</abbr>”. The <code><abbr>tz</abbr