Can ONE variable select how ANOTHER variable is used?

Fluent
#1

On https://www.projectfluent.org/ there is a good example of the FTL-file Fluent syntax:
(I don’t know why some words are in bold below…)

tabs-close-tooltip = {$tabCount ->
    [one] Close {$tabCount} tab
   *[other] Close {$tabCount} tabs
}

But can ONE variable select how ANOTHER variable is used? Something like this:

about-the-S-value = {$IndexCount ->
    [zero] In this case S is larger than {$S-value}.
   *[other] In this case S is smaller than {$S-value}.
}
#2

Yes, you can reference any variable you want inside a pattern of a select expression.

Your example hints at something else, though, that you’re trying to put logic into a single message. Select expressions are designed to be independent in each localization. You shouldn’t assume that just because English uses one, all locallizations would do, too. A more detailed explanation is on https://github.com/projectfluent/fluent/wiki/Good-Practices-for-Developers#prefer-separate-messages-over-variants-for-ui-logic.

#3

OK. I will follow the recommendation to have 2 messages instead and let Python choose between them.