What's the correct format for allow & disallow on peer details for the trunks?

What’s the correct format for allow & disallow on peer details for the trunks?

Unfortunately the tool tip doesn’t give an example, are any of these right?
disallow=all
allow=g729,ulaw

disallow=all
allow=g729&ulaw

disallow=all
allow=g711,g729

disallow=all
allow=ulaw&g729

TIA

This is why keeping track of the track tickets to see changes is important.

It looks like they all work now, just depends on the version. The order does not matter and the ampersand is the most conservative connector as it works in all versions of FreePBX.