Searching for calendar items older than a specific date with search-mailbox and AQS

I need to find the total size of all calendar items in a mailbox older than a specified date using PowerShell through the search-mailbox cmdlet's searchquery parameter.  My problem is that I cannot find a complete list of Calendar item properties to use in search queries.  The AQS page doesn't have a complete list of properties for a Calendar object.

I'm using code from the ArchiveStatisticsPlanner.ps1 script as a base and the only date properties I know of are the sent and receive properties (see below.)  The basic start, end, date properties generate errors in the query.  How can I find all Calendar items older than say, 1/1/2013?

Sample:

$MBXSearch=Search-Mailbox-Identity$MBX-SearchQuery"kind:calendar sent:<=$QueryDate OR kind:calendar received:<=$QueryDate"-EstimateResultOnly-DoNotIncludeArchive