Transferring Funds to Post Office Account

Quick question:

I have a Post Office account here in Taiwan, and am looking to transfer funds from my account abroad, online.

However, I am not so sure which numbers I should use in the online banking system - the post office people didn’t seem too clued in either so I thought I’d turn to the forum for help.

Basically, the savings booklet has 3 sets of numbers on it: the first is 郵局代號 which is 700, which specifies Chunghwa Post Office as far as I can tell; the second 局號 (含檢號)and the third 帳號(含檢號).

Now, my online banking page asks for either account number or IBAN, so the latter is out (European only afaik), but what combination of numbers do I plug into the account number? The 3 numbers above?

Any help appreciated!