For completeness using text formatting that would be included in the rules change, here is the full text of what Charlie stated above in the full context of the rules with surrounding paragraphs.
Original:5.12.1.2 Mainsail shall be manufactured from woven ply polyethylene terephthalate ("PET"), such as Dacron®, or woven ply polyethylene naphthalate ("PEN"), such as Pentex®. The spinnaker shall be manufactured from woven ply nylon.
5.12.1.3 Sailcloth in the #1, #2 and #3 Genoa is not restricted.
This change in approved sailcloth goes into effect no later than October 17, 2005. Individual
J30 Class Districts may adopt this change for local events at an earlier date.
5.12.1.4 Sail numbers shall be placed immediately above the third batten (#2 sewn from the head of the mainsail) on the #1 and larger genoa in line with the mainsail numbers and on the spinnaker. The starboard or forward number shall be on top.
5.12.1.5 Genoa #2 is optional and does not need to be on board while racing.
5.12.1.6 Numbers shall be of the following dimensions in solid black, red, green or blue: height = 380mm, width = 254mm, thickness = 57-77mm, spacing = 77mm.
5.12.1.7 Windows. There is no limit on the number or design of collision, telltale, or spreader tip windows on the mainsail or genoas.
5.12.2 Mainsail
5.12.2.1 Minimum cloth weight is 6.25 oz.
Proposed:5.12.1.2
Mainsail shall be manufactured from woven ply polyethylene terephthalate ("PET"), such as Dacron®, or woven ply polyethylene naphthalate ("PEN"), such as Pentex®. The spinnaker shall be manufactured from woven ply nylon.
5.12.1.3 Sailcloth in the
mainsail, #1, #2 and #3 Genoa is not restricted. This change in approved
main sailcloth goes into effect no later than
1 May 2013. Individual
J30 Class Districts may adopt this change for local events at an earlier date.
5.12.1.4 Sail numbers shall be placed immediately above the third batten (#2 sewn from the head of the mainsail) on the #1 and larger genoa in line with the mainsail numbers and on the spinnaker. The starboard or forward number shall be on top.
5.12.1.5 Genoa #2 is optional and does not need to be on board while racing.
5.12.1.6 Numbers shall be of the following dimensions in solid black, red, green or blue: height = 380mm, width = 254mm, thickness = 57-77mm, spacing = 77mm.
5.12.1.7 Windows. There is no limit on the number or design of collision, telltale, or spreader tip windows on the mainsail or genoas.
5.12.2 Mainsail
5.12.2.1
Minimum cloth weight is 6.25 oz. The mainsail minimum bag weight (without battens) shall be not less than 13.6 kilos (30 US pounds).