[APBeta] [OT]:Converting stellar sprectra to surface temperature

[RPEHLM]

Hi folks,

This is likely to be a 'how long is a piece of string question' :)

Is there an accepted 'standard' for converting stellar spectra 
classifications to surface temperature?  For example mapping M0 to 2500K 
or G2 to 6200K.  I've looked at a few and they all vary by 500-750K to 
each other.  This is kind of related to APv2 because I'm writing a 
script library that could use such a conversion routine.  Hmmm, maybe I 
feel a feature request coming on! :)

Regards
Robin