Pulley timing marks

Hi all,

Bought a timing light to adjust the timing on my 1300 72 beetle (1600tp). I identified TDC mark but then noticed it only has 1 timing mark...i read on here they normally have 2 so how can i if this is the 7.5 btdc or 10 btdc?

only real safe method is to calculate, mark out and measure

Have a read here
http://www.vw-resource.com/tune-up.html#marks