Dear Yong Peng and friends,

Dhammapada-Atthakatha explains that 'dhammaa' is here the mental
processes - recognition (sa~n~naa), feeling (vedanaa) and intention
(sa"nkhaara).

Dhammaati gu.nadesanaapariyattinissattanijjiivavasena cattaaro dhammaa
naama. Tesu–
“Na hi dhammo adhammo ca, ubho samavipaakino;
adhammo niraya.m neti, dhammo paapeti suggatin”ti. (theragaa.
304; jaa. 1.15.386)–
Aya.m gu.nadhammo naama. “Dhamma.m vo, bhikkhave, desessaami
aadikalyaa.nan”ti (ma. ni. 3.420) aya.m desanaadhammo naama. “Idha
pana, bhikkhave, ekacce kulaputtaa dhamma.m pariyaapu.nanti sutta.m
geyyan”ti (ma. ni. 1.239) aya.m pariyattidhammo naama.
“Tasmi.m kho pana samaye dhammaa honti, khandhaa hontii”ti (dha.
sa. 121) aya.m nissattadhammo naama, nijjiivadhammotipi eso eva.
Tesu imasmi.m .thaane nissattanijjiivadhammo adhippeto. So atthato tayo
aruupino khandhaa vedanaakkhandho sa~n~naakkhandho
sa"nkhaarakkhandhoti. Ete hi mano pubba"ngamo etesanti manopubba"ngamaa
naama.

Mano here is sixth faculty of perception
http://www.lioncity.net/buddhism/index.php?showtopic=22507

One can see how 'mano' conditions mental processes, on the chart of
dependent co-arising

http://dhamma.ru/lib/paticcas.htm

Metta,
Dmytro