Excerpt from change request document:
This split is proposed based on findings from formal linguistic survey work on the Phula languages of Yunnan Province, China, carried out from 2005-2006. Eight of the 40 villages visited during this research period were closely affiliated ethnolinguistically with ISO code [ymj]. Research components explored lexicon, identity, contact and intelligibility, and the results point to five synchronically distinct languages originally subsumed under [ymj]. Communication and transportation have traditionally been limited between these varieties, though they are all closely related phylogenetically. The most vital and prototypical Muji variety, Southern Muji, also has the largest number of speakers. Rationale for identifying the other four languages as distinct from [ymj] is given below.
[ymx] or Northern Muji speakers yeilded a mean score of .60 on a recorded text test from [ymc] with a high standard deviation of 24 suggesting that a mobile demographic has learned intelligibility with [ymj]. Anecdotal and perceptual information from [ymx] and [ymc] speakers alike confirms a distinction between the two, and speakers report significant learning time (longer than two months) being required in order to communicate in their respective Muji lects. A similar situation is reported between [ymx] and [ymz].
The smaller [ymi] and [ymq] (Moji and Qila Muji) varieties have apparently been separated from Muji proper for centuries and evidence numerous unique lexical and phonological characteristics as a result of independent change and language contact with other varieties. Lexical similarity in core vocabulary between these two and the other Muji varieties is lower than 60%--sufficiently low to posit the presence of mutually unintelligible synchronic languages without resorting to formal intelligibility testing. Although [ymq] shares a
[ymz] or Muzi speakers also scored low on the [ymc] recorded text test (.50) , and [ymx] speakers report that a bride who married out from their area to a [ymz] village required six months to one year before she was able to function in the [ymz] variety.