[syslog-ng] ESTRING terminated by a colon?

Hello, Hopefully this is a new question.  I've been trying to write patterns for error messages sent by Cisco IOS devices.  For example: 20: *Feb 28 15:00:08.556 AKST: %LINEPROTO-5-UPDOWN: Line protocol on Interface BVI1, changed state to up A pattern that works: @NUMBER:seqno@: @ESTRING:CISCO.DATE: %@LINEPROTO-5-UPDOWN: Line protocol on Interface @ESTRING:arg1:,@ changed state to @ANYSTRING:arg2@ But to avoid capturing the colon an space, the end-match needs to be ": "  (i.e. colon space), like so: @ESTRING:CISCO.DATE:: @ However, I'm unsure how to quote the colon, when it's already the ESTRING param delimiter? Thanks