Waterproof leggings sizes

[wannabeek]

I'm trying to order some waterproof leggings using the new online system and the size options available are a bit peculiar. It goes ML, MR, SL, SR, XLR, XSL, XSR and LR. I used a spare pair at work once and I could have fit three of me into them so I'd rather choose a more compact version if possible. Any ideas what the sizes on offer mean?

[Lazycarton]

I would assume that M is Medium waist L is Long (33" inside leg) R is regular (31" inside leg ) etc

[wannabeek]

So it goes medium, small, extra large, extra small, not quite so extra small, then medium? Wow, that's as chaotic as most housing developments round here, I feel right at home!