It was codified in the pronouncing dictionary Deutsche Bühnenaussprache, edited by the German scholar Theodor Siebs, and first published in 1898.
A voiced uvular fricative [ʁ], used extensively in contemporary Standard German, is not allowed.
[5] In loanwords from Latin and Ancient Greek, the word-final /ə/ is realized as a short, tense [e] so Psyche 'psyche' is pronounced [ˈpsyːçe] rather than the standard [ˈpsyːçə].
[4] As in Standard German, syllable-final obstruents written with the letters used also for syllable-initial lenis sounds (⟨b, d, g⟩ etc.)
The voiceless plosives /p, t, k/ are aspirated [pʰ, tʰ, kʰ] in the same environments as in Standard German but more strongly, especially to environments in which the Standard German plosives are aspirated moderately and weakly: in unstressed intervocalic and word-final positions.