Competition judging

At last nights meeting when Roger was summing up the clubs success at Connors Quay, Roger made reference the the international method of how the judges award points to the images with a maximum being 15 points. Can anyone explain to me how this works please; are there categories for the points to be awarded etc.
I would appreciate some feedback if possible.
John Moore

For major exhibitions there are usually 3 judges, and they each have a keypad with keys 2, 3, 4 & 5, giving a marking range of 6 to 15 - although in some exhibitions the judges have a 1 button, and I have had images receive 3 marks in an exhibition!!!

So generally 5 means the judge definitely wants the image in the exhibition, and may consider it for an award, 4 the judge thinks the image should be in the exhibition, 3 a near miss not quite good enough, 2 the judge considers the image quite poor.
Marks are valid for that particular exhibition, and depends on the quality of the rest of the images. So a judge could quite easily give an image a 5 in a small exhibition where is was the best of the bunch, and then a 3 in for the same image where it was up against much better images,

Thanks Tim, that clears it up for me perfectly.
John