an exoticized version of one of the secondary characteristics of the traditional model the original glottalic theorists had objected to. Nevertheless, proponents of a revised model like Weiss (2009) acknowledge the rarity of bilabial implosives, suggesting that they became *w before consonants, citing the strongest reconstructed roots containing *b (from pre-PIE [ɓ]) were pre-vocalic like *bel- "strong" and *bak- "stick" in contrast to the preponderence of PIE *wr-, *wl-. This ɓ > w sound change is attested in Proto-Tai to Longsheng in addition to the similar PT ɓ > v in Yuanyang and Menglian. Alternatively, Weiss (2009) suggests that the implosive series could instead be nonexplosives, found in 20% of the world's languages like in Ikwere. Phonation alternative Another alternative to the glottalic theory proposed by James Clackson bases the contrast on phonation. Observing that the traditional voiced aspirated series is preserved in languages like Sanskrit not as true voiced aspirates but as voiced consonants with breathy or murmured voice, Clackson suggests the contrast between voiceless, voiced and voiced aspirates could be reframed as stops conditioned by three phonations: voiceless, creaky or stiff voice, and breathy voice. That, he argues, is typologically more common than voiced aspirates without voiceless counterparts: Schirru has also suggested that the voiced aspirated stops could be better analyzed as having the feature [+slack vocal folds] or [−stiff vocal folds]: Frederik Kortlandt As mentioned above in "Direct and indirect evidence", Frederik Kortlandt in particular has argued for these traces of glottalization being found in a number of attested Indo-European languages or the assumption of glottalization explaining previously known phenomena, which lends the theory empirical support: Direct Sindhi reflects the non-aspirated voiced series unconditionally as implosives. In Germanic, some Danish dialects have clusters of a glottal stop followed by a voiceless stop (vestjysk stød) which correspond with the Proto-Germanic voiceless stops, deriving from the allegedly-glottalized PIE series. In Balto-Slavic, glottalization is also directly attested, in the broken tone of Latvian and Žemaitian. Potentially word-final glottalization in English Dialects of Armenian also show glottalization, having inherited it from Classical Armenian. Indirect In both Latin (Lachmann's law) and Balto-Slavic (Winter's law), vowels are lengthened before a "voiced" consonant. features such as preaspiration in Icelandic and Faroese and sporadically in Norwegian and certain instances of gemination in Swedish and High German Problems Arguably, the minority status of most of the languages which provide the allegedly-certain direct evidence for the theory