Did I not hear my name invoked in this thread? I must respond.....:)

H.S. writes:

>Unsurprising. The same probably also happens in Hokkien, it's just that
>I'm not conscious of it. Tones are not fixed, rigid features; the
>"official" tones are often just what they would be in isolation. When in
>combination, they tend to mold and merge with each other, leading to tone
>sandhi and "intermediate" tones which don't always correspond to one of
>the "official" tones.

Precisely. Tones are relative to one another. In Mandarin, at the
beginning of an utterance, a first tone is a full-fledged 55, but by
the end of the utterance, it may downgrade to 33. Of course, all
other tones must adjust to keep the relativity intact.

  Florian Rivoal wrote:

>  > A total count of all the possible variants(only on the material i have
>>  read up to now, so maybe there are more) would bring the theorical 5 to
>>  a total amount of 9, or even 12 if you count the glotal-stoped tones as
>>  distinct one.
>Well, for the longest time I've considered Hokkien as a 4-tone language
>myself; but apparently some linguists think otherwise, and decide to
>combine long/short into the definition of tone as well.

If you leave out the "clipped" tones, I could see five. But the seven
is correct if you want to take into account all the tone sandhi
variables. Tones 4 and 8 (remember, there is technically no tone 6)
when followed by proper ending-consonants (p, t, k) behave
differently than when they end in a glottal stop (which I have never
heard as distinctly as in Shanghainese).

>  > But i have always seen shanghaienese refered as a 5 tone language. Does
>>  this mean every body is wrong, and it is not a 5-tone one, or does this
>  > mean it allows off-tones tonal variations?

Again, as H.S. rightly points out, tones are not absolutes, but
relatives, so something being a pure 53 throughout a conversation
would be unusual. I like H.S.'s term "tonemes".

>  > an interesting thing to note is that expect someone with linguisicts
>>  background, shanghainese people will tell you their language has NO
>  > tone.

This is interesting. When I've heard natives talk about their own
dialect, they usually inflate the number of tones (e.g.: Cantonese
speakers will say they have 10+ tones; one Taiwanese speaker I
overheard on a bus told a wayward foreigner that there were 12+ tones
in Taiwanese, etc.)