點解銀紙上面都有"承董事會命"e 5個字?

承董事會命 = By Order of the Board of Directors
It means the resolution was passed by the Board of Directors of the company in a meeting. Now, the company secretary or the director is only acting on behalf of the Board to give such a public statement or announcement.

2008-02-24 17:50:19 補充：
The person signing the bank note is authorised by the board of directors to do so on that date as stated for the issuance of that bank note.