syslog include filter that adds a text string to events

I would like to add a text string like "ASM_system_error" to every local3 event of level critical to emergency since syslog doesn't include the severity level in the log event itself (unless we have something configured wrong). Right now the include statement is something like this:

sys syslog include "filter f_waffilter { facility(local3) and (level(emerg) or level(alert) or level(crit));};destination waf_udp { udp(9.9.9.9 port(9999));}; log { source(local); filter(f_waffilter); destination(waf_udp);};"