Excerpt from change request document:

Lexical similiarity of Dari and Tangshewi is between 86% and 90%. Comprehension testing of Eastern Farsi (Dari) showed that Dari is highly intelligible for the Tangshewi people. The Tangshewi call the valley they live in Tangshew valley but not their speech variety. No one ever mentioned a language called Tangshewi as his mother tongue. The Tangshewi themselves explain that they speak Dari, acknowledging that their dialect is slightly different.