Is there a term for a "placeholder" word (like Acme Widgets) that isn't a "euphemism" as such?

I'm after a word similar to "euphemism" but without the negative/taboo nature of a euphemism, more of a generic term. I would characterise it as a "anony-nym" but that's not a thing!

For example:

"Acme Widgets" in place of a specific company name, e.g. "When I worked for Acme Widgets, I had a situation where I had to..."

"Jane Doe" in place of a specific person, e.g. "The website sees that Jane Doe has logged in, and gives a personalised list of music that Jane has listened to recently."

Solution 1:

I would argue that "placeholder" is exactly the word you are looking for.

Wikipedia suggests in this article that "kadigan" or "cadigan" has also been used for the specific sense you are using, of a generic name or word that stands in for another one that is irrelevant or forgotten. That's fun to know, and technically closes a semantic gap, but if you want people to actually know what you're talking about then I wouldn't recommend using it.

An analogous idea that I love from computer programming is that of metasyntactic variables.