The Simayamka (literally "All Who Speak [the] Siye [language]") have the atheist (as it were) version of this. They primarily live in towns along the River. They don't give a fig about what gods you worship (which is why they tolerate Christian missionaries), but the Guild of Scholars - note that the linguistic expertise is presumed - controls the grammar of Standard Siye. Contracts written in anything other than Standard Siye or standard Ulok are invalid, as are oaths sworn ungrammatically. Using non-Standard Siye in an official speech can get you fined. Here's an example: it is rude to refer to a superior (and technically, anyone else) using the instrumental suffix -ki alone (one should use at least an extra suffix -me-/-ne-). The charge, however, will not be rudeness; it will be using poor grammar! Since the Simayamka have a Iron-Age level of organization, this is not as well-enforced as the Guild would like. But the ONLY reason the dialectical Simayanga ( -mk- [~k] > -ng- [N]), the easternmost group of Simayamka, are tolerated as Simayamka is this: they are clearly not Ulok-speakers, and traditionally there are only two languages: Ulok and Siye. It's clearly not Ulok, so it must be poor Siye!