name=rePattern with optional ignore and capture strings
description=Example from https://code.google.com/p/otroslogviewer/wiki/Log4jPatternLayout

type=log4j
rePattern=(\\S+ \\S+)\\d (\\S+) +(\\S+) +(?:\\[TID:(\\d+)?[^\\]]*\\] )?(?:User:(\\S+) )?(.*)
dateFormat=yyyy-MM-dd HH:mm:ss,SSS
charset=UTF-8

TIMESTAMP.group=1
# APPLEVEL is a Custom field.  Displayed as key=value pairs in OLV Properties column.
APPLEVEL.group=2
LEVEL.group=3
THREAD.group=4
NDC.group=5
MESSAGE.group=6