An outstanding issue in Tashlhiyt Berber phonology is the status of the short central vowel (schwa) that appears in certain consonant clusters, and its relation to the remaining (peripheral) vowels in the language. We show that within Tagnawt, a secret language in Tashlhiyt Berber used by women, peripheral vowels are underlyingly long, in that they connect to two skeletal positions. They become unassociated when they have access to only one position. Then, depending on phonotactic conditions, this skeletal position remains empty or surfaces as schwa. In particular, it is demonstrated that Tagnawt formations are all built upon a fixed-shape template fundamentally designed to accommodate three root-consonants. Accordingly, when the Tashlhiyt input is quadriconsonantal, one root-consonant is regularly discarded. In certain cases, however, all four consonants are maintained, except that a schwa systematically appears in one of the vocalic positions where the vowel a normally surfaces. This cannot be accounted for unless the proposal on the representation of peripheral vowels and schwa is assumed.