anchor chain

I've a 1980s Muir windlass/gypsy designed for 3/8 short link chain,

I'm looking to replace my 45 metres or so of chain with 60 metres to meet a minimum requirement for an event I am thinking of participating in. Muir assure me that 10mm chain will work with my gypsy, even though the pitch is slightly different to 3/8.

Be that as it may, I am curious if anyone else finds it odd that Muir and others promote "Galvanised G50 Grade 'L' Short Link" chain.

Here's a couple of examples:
www.whitworths.com.au/muir-anchor-chain-galvanised-g50-grade-l-short-link
keoghs.au/keoghsmarine/muir-anchor-chain-10mm-galvanised-g50-grade-l-as2321-f811137/

According to Australian Standard 2321:2014 Grade L is G30 and G50 is grade P. As I read it a chain cannot be "G50 Grade L". This suggests those labelling chain as such do not understand chain grades.