Baertram,
TYVM for the info and the explanation. I will look at that template page for direction.
As far as the difference in "." and ":", I was a little confused on that. I have never seen both being used, generally only one or the other based on language syntax.
If you look at
https://wiki.esoui.com/Writing_your_first_addon, the "Basic Skeleton Code" section does exactly the flip-flop you mentioned. I haven't coded in Lua in over 10 years (not since I played WoW) and didn't feel comfortable deviating from the tutorial until I had a working framework that I could go back and break.
But, I will revisit the lua.org manual for more guidance as it has been some time.
On a side note, what version of LUA is ESO using?