Can you clarify this for me:

example A - 6 bids come in in the last 10 minutes, auction extends for 1 hour,
or
example B - 1 or more bids in last 10 minutes extends 10 minutes, during which 1 or more further bids extends a further 10 minutes, etc.

Which is it? or both? the way it is worded, it is potentially open ended...? Is there a maximum extension?

Sorry I am not familiar with this system, better to know before bidding!

Thanks