If you use EEM applets with action syslog commands, the messages generated by those commands will be displayed in the same format as the debugging messages, regardless of their severity. This might be a problem if you decide to use different timestamps for debugging and regular syslog messages (or disable debugging timestamps completely). For example, the following configuration ...
service timestamps debug uptime... produces these messages after an interface failure ...
service timestamps log datetime
event manager applet Serial_Down
event track 1 state any
action 1.0 syslog priority errors msg "IP routing on Serial 0/1/0 is $_track_state"
Aug 14 11:18:32: %LINK-3-UPDOWN: Interface Serial0/1/0, changed state to up
1d16h: %HA_EM-3-LOG: Serial_Down: IP routing on Serial 0/1/0 is up