classification of compositional data

[Gabriel Baud-Bovy <gabriel@shaker.med.umn.edu>]

What method(s) should be used to classify compositional
data (i.e., proportions)?

In particular, is it possible to use discriminant analysis?

Is there any example (book, reference, etc.) how to do it 
in S-plus?

Thank you for your help.

Gabriel Baud-Bovy

PS: I'll post a summary of the responses.