NS Name Tag: Format? Can Put Any Name? English Name? How?

What can i put as my initials for my name tag if my name is e.g. Tan Ah Kow John should it be A.K.J. Tan? or just A.K. TAN?

There are a few options:

1. A K TAN

2. J A K TAN

3. JOHN TAN

As long as do not exceed 10 letters (including spaces)