'bases of meritorious action'.
In the suttas, 3 are mentioned
consisting of giving (liberality; dāna-maya-p.),
of morality (sīla-maya-p.) and
of mental development (meditation; bhāvanā-maya-p.).
See D.33; It.60; expl. in A.VIII.36.
Commentaries have a list of ten (dasa p.) which is very popular in Buddhist countries:
(1)-(3) as above,
(4) reverence (apaciti),
(5) service (veyyāvacca),
(6) transference of merit (pattānuppadāna),
(7) rejoicing in others' merit (abbhānumodana),
(8) expounding the Doctrine (desanā),
(9) listening to the Doctrine (savana),
(10) straightening one's right views (rectification of views; ditthujukamma). -
Expl. in Atthasālini Tr. 209ff.
See 'The Advantages of Merit', by Bhikkhu Khantipalo (BODHI LEAVES B. 38).