Mandarin Neutral Tone: Tone Value? One of my dialectical dictionaries takes tone value 21 and compares it to Mandarin's neutral tone.

The same tone, coincidentally enough, had been described in the same way to me by a local native speaker (i.e.: tone value 21 - Mandarin's neutral tone).

While it's logical to me, it does seem like a little bit of a stretch.

Cantonese's fourth tone (at least according to jyutping) is also tone value 21, think 唔 m4 (meaning 不). 

I can't seem to find any information talking about tone values with the neutral tone, I guess because it's not considered a tone to begin with. 


does Mandarins neutral tone have any tone values associated with it?
if so, does it differ by region?
is it reasonable at all to say that tone value 21 is equivalent to Mandarins neutral tone?
The neutral tone doesn't have a fixed value; it's phonetic realization is largely determined by the preceding tone:

Also called fifth tone or zeroth tone (in Chinese 轻声 [輕聲] qīng shēng, literal meaning: &quot;light tone&quot;), neutral tone is sometimes thought of as a lack of tone. It is associated with weak syllables, and thus usually comes at the end of a word or phrase, and is pronounced in a light and short manner. The pitch of the neutral tone depends almost entirely on the tone of the preceding syllable. [...]
First ˥   ˨ 2 玻璃  bōli    glass   ˥.˨
Second ˧˥ ˧ 3 伯伯  bóbo    uncle   ˧˥.˧
Third ˨˩  ˦ 4 喇叭  lǎba    horn    ˨˩.˦
Fourth ˥˩ ˩ 1 兔子  tùzi    rabbit  ˥˩.˩