http://cgi.ebay.co.uk/Wolfcraft-300mm-Angle-Measure-Square-Protractor-5205_W0QQitemZ390086083676QQcmdZViewItemQQptZUK_Measuring_Tools_Levels?hash=item5ad2f1445c Does anyone no what the vertical measure holes on the square are for,they are 9.5mm,17mm,21.5mm,28mm , 33.5mm and 37mm.They are on...