Mr.Somkiat,
We use logic
resent to generate the nested body content of this tag if the specified value is present in this request.
I hope this
link will give you more info than mine... There are many other tags in the Logic library explained there in that link...
Hope it helps...
Co-author of SCMAD Exam Guide, Author of JMADPlus
SCJP1.2, CCNA, SCWCD1.4, SCBCD1.3, SCMAD1.0, SCJA1.0, SCJP6.0