I think this implies a meaning of "the" that doesn't actually exist in modern english.

"The" often refers to a group or category.

"The other" is actually a phrase I would take to be incredibly inclusive in meaning if not followed by another specifier (it means "the category of everything that is not us").

"The alternative" is similarly a category structure. It's a singular category, made of many possible members, or alternatives.

You may still only pick a single alternate for each case, but that does not mean that a category of multiple possible alternative choices does not exist.

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All that said, sparkfun is messing up by labeling this DE9. Spoken as someone who's done quite a bit of serial communication work. The defacto industry term is DB9, whether they like it or not, and most searching/purchasing will be done using that term. This is a "technically correct" fun article, with a name that would immediately mean I don't ever find this product (and would not purchase this product) unless they highlight that this is a DB9 breakout board with a bad name.

Simple test? Amazon has more than 4000 results for "db9 cable" and only ~110 results for "de9" cable. Even specialty sites like McMaster, which are usually pretty particular with their terms are happily calling this a db9 connector: https://www.mcmaster.com/products/connectors/computer-connec...

> I think this implies a meaning of "the" that doesn't actually exist in modern english.

> "The" often refers to a group or category.

But this does not hold for the meaning of Latin "alter, altera, alterum" (the other one), from which the German and English word "Alternative"/"alternative" is derived.