Someone deacronymize plz :(

All various motorcycle helmet standards. ECE is the EU standard, DOT is the US Department of Transportation standard, FIM is another, stricter EU standard (Functional Independence Measure), and Snell is not an acronym but is an independent safety testing organization.

FIM is Federation Internationale de Motorcyclisme - here referring to their standard for MotoGP and World Superbike helmets.

ECE is a United Nations standard that the EU has chosen to require for helmets sold in the EU.

Ah, thanks! Admittedly I Googled that one, it didn't feel right...

Also when I was buying my motorcycle gear (8 years ago) the general conses I recall is that ECE ~= DOT. Not sure what OP means regarding DOT certification.

ECE is stricter than DOT, although it has a couple of shortcomings.

It sounds like upthread the poster thought that ECE doesn't allow half or 3/4 helmets, but they do.

DOT:

- is nearly 50 years old without meaningful changes to reflect half a century of head injury and brain injury research

- has significantly lower standards for how much force can be transmitted through the helmet to your skull - well within values that commonly cause skull fracture

- does not have any brain injury criteria for rotational trauma

- does not have any independent random testing, and limited independent random test studies have found 50% of labeled helmets don't meet the standard

The last point is especially frightening! ECE has fixed all of these issues. Fortnine's videos on this (and the problems with Snell 2020R/2020D) are a great place to learn more.