hi nicepants.
In Japan, descripting by 24hour is standard.
Only some old fassioned people use 12hour.
I'm interested with the fact that 24hour is only used in military in your country.
BTW, this is a lanugage issue.
What language do you use?
Edit language/(your language)/pical_constants.php
eg)
// format for date() see http://jp.php.net/date
define('_PICAL_DTFMT_TIME','a g:i') ;
// set your locale
define('_PICAL_LOCALE','en_US') ;
// format for strftime() see http://jp.php.net/strftime
define('_PICAL_STRFFMT_DATE','%d %b %Y (%a)') ;
define('_PICAL_STRFFMT_DATE_FOR_BLOCK','%d %b') ;
define('_PICAL_STRFFMT_TIME','%p %I:%M') ;