It really is a funny old world eh .. Just 4% of the worlds population seem to think that THEY ARE THE WHOLE WORLD & whatever they think rules everywhere.
The Glock "First Generation" model typifies how U S models designation can become 'the standard' ... something like "The Big Mac Index" - where the cost of a U S hamburger is used to measure national economies around the planet (PPP - Purchasing Power Parity).
.. The U.S. Gun Writers Are WRONG
The true original 1st Generation Glock 17 did not have any serial number on the bottom of the polymer (Nylon) Frame .. I think a few U S gun writers now recognise that there is a generation prior to 'Gen 1' that they might call the "Austrian Army Model" - but that was actually sold worldwide before Glocks were imported into America.