It has come to our attention recently that several sailmakers have developed spinnakers which may be flown with the luff as presented for measurement being there solely for measurement purposes, and when the sail is set with the luff folded back presenting a section of the body of the sail as the leading edge when set. 

IRC Notice 2016-01 addresses this, click here to download the Notice in PDF format (English & French)

Issued by the IRC Technical Committee
8 December 2016