NDC in Log4J

Log4J manual told me about Nested Diagnostic Contextshttp://logging.apache.org/log4j/docs/manual.htmlBut I didn't understand this conception. May you help me with it?Where & when I need to use it?
[236 byte] By [655489dbes@isd.dp.uaa] at [2007-11-26 12:19:12]
# 1
Does anybody know the answer?
655489dbes@isd.dp.uaa at 2007-7-7 14:59:55 > top of Java-index,Archived Forums,Socket Programming...