Specify and allow Private Terms

[Pike]

We've used the term private in a lot of ways by now, I'd like us to re-introduce it for entries that are internal to a particular localization.

The primary use-cases right now would be platform-dependent phrases for example in Japanese.

We first talked about this in #62.

[stasm]

To make sure we're on the same page, do you mean private as in not checked by tools like compare-locales?

#62 mentions a grammar solution to this: --private-term.

If the only difference between -term and --private-term is the compare-locales use-case, could we achieve the same result with a @private decorator/semantic comment? (#16).

[Pike]

I mean private in the sense that

• they're localizer-generated (i.e., pontoon),
• or even reference-localization specific (i.e. pontoon would not require a localization thereof), interesting problem around what to localize then
• they're not reported as missing or obsolete
• they're checked for validity and errors
• they're including in term ref checks

Their specification would likely also entail best practices on where to add then when a tool like pontoon is used to create one.

As for implementation, I'm not sure if I like or dislike semantic comments for that. Using semantic comments is the invitation to use group or file comments to denote private terms in a file, or a kind of glossary file globally. That's tempting, but that also makes it more involved to write tooling support for it.

And Semantic comments have the downside of not being ready-to-use right now :-/