data.sql must be updated for [DEV-444].
in table 'help_items' on keys: log, logrt, eventlog add ",<mode>" at end of key parameters and update it Description.

Also, i wanted to ask why the documentation page http://www.zabbix.com/documentation/1.8/manual/config/items
comma (parameters separator) is presented inside the angle brackets <> and not between them?
Unify with "data.sql" please, probably between the brackets is clearer, logical and correct.
This applies not only log, logrt, eventlog.