In case you’re not one of those 80.000, you can correct your mistake by doing it now below. Or, if you prefer, you can also read the full introductory chapter we wrote: “Object Constraint Language (OCL): A definitive guide”
While the slides are from 2012 (which explains all the mentions to my former AtlanMod team), 90% of what it says is still valid nowadays since the core of the language has not really evolved in all these years.
The slides cover the motivation behind the language (i.e. why we need OCL at all), the language core concepts, its syntax (with plenty of examples), the OCL type system, the 3-valued logic, operations for iterator and collection expressions and plenty of more advanced topics (casting, null values, recursion,…).
(and yes, I’m fully aware that this does not mean people actually like the OCL, they may be just interested in it or, even worse, forced to be interested in it, but just let me daydream for a while ok?)