It is also called Natural sort order.
"It's hard to find information on natural sorting"-Jeff Atwood on Coding Horror.
And it seems true today as the Wikipedia entry seems pretty bare.
The main difference is that Definition 1 allows decimals while Definition 2 does not. For example I have the list ["t8.1", "t8.11", "t8.2", "t7.2", "t7.11"].
Definition 1 would yeild: ["t7.11", "t7.2", "t8.1", "t8.11", "t8.2"].
Definition 2 would yeild: ["t7.2", "t7.11", "t8.1", "t8.2", "t8.11"].
Perl follows definition 1 (which is where I found it.
MATLAB uses definition 2 for non-version numbers.
Dave Koelle implements definition 1 for his examples but says it's a 'glitch' and thus supporting definition 2 as correct. In most the linked code, the code treats '.' as a string but what if it was a decimal in a numeric substring? Dave Koelle notes this as a glitch by saying "There is currently a glitch when it comes to periods/decimal points - specifically, periods are treated only as strings, not as decimal points.".
To me, the word numeric would imply decimals but in practice it seems that this is not the case unless specifically noted to include decimals.
What does Alphanumberic/Natural Order Sort mean exactly without additional qualifiers? For example: In "Natural Order Sort with decimals", "with decimals" would be an additional qualifiers. Which definition is correct for "Natural Order Sort"?