The timestamp in the change set details for the ClearCase sometimes uses 'HH:MM:SS (AM/PM)' and sometimes uses 'HH:MM:SS' (24-hour clock). Here's an example:

#114 (Sep 28, 2010 4:55:19 PM)
1. deliver gkaas_Product1 on 9/28/2010 16:45:43. — gkaas / detail
#113 (Sep 28, 2010 1:01:29 PM)
1. deliver gkaas_Product1 on 9/28/2010 12:52:07. — gkaas / detail
#111 (Sep 28, 2010 10:16:00 AM)
1. deliver rbuss2_Product1 on 9/28/2010 10:04:21 AM. — rbuss2 / detail

The first 2 use a 24-hour clock and the third uses a 12-hour clock annotated with AM/PM. This makes it a bit inconvenient for use with the hgca plugin.