Window/Glass Codes

[bexwoods]

Hey guys can anyone help me understand the significance of each part of the E code on windows?
Specifically the bottom row (dots and single digit)… what does it mean

I’m trying to work out if I need to change the quarter lights as my old door has 3 dots and a 9 and my replacement has 2 dots and an 8??

[bexwoods]

Never mind I’ve sussed it!
It’s the date of manufacture

[rix313]

I think you'd have to have found the most boring human alive if they picked up on that in an MOT or an inspection anyway Bex