Magic Word "NOSEP"

This is the parser test that is in MediaWiki core for it:

!! test
Check noCommafy in formatNum
!! options
language=be-tarask
!! input
{{formatnum:123456.78}}
{{formatnum:123456.78|NOSEP}}
!! result
<p>123 456,78
123456.78
</p>
!! end

Makes one think of "no separators", but if it's both decimal and thousands separators this would mean not changing nothing, as in that test example. In fact it's not documented...

It is in fact no-op for many languages, but not for those who use different digits.