There is only one file type that uses the .OLK14EVENT extension:
Outlook Calendar Event File
File created by Microsoft Outlook for Mac, an email and calendar management application; stores data for an event on the Outlook calendar, including the date, time, and invitees; used for saving a local cache of events, even if the calendar is saved remotely.
OLK14EVENT files are saved to subdirectories of the following directory in Mac OS X:
[user]/Documents/Microsoft User Data/Office 2011 Identities/Main Identity/Data Records/Events/
Updated: September 12, 2010