ah actually based on other comments here i believe it means 13/2054 - 14/0430. ie the 13th, 20:54 to the 14th: 04:30.
From the advisory:
EFFECTIVE TIME: 132054 - 140430
SIGNATURE: 26/11/13 20:54
13 is the date, 2054 is 20:54. So the advisory expiration time is Nov 14 04:30.UTC?
maybe the last two numbers are a time range for which the thing is effective? and it's over now?