conserved amino acid changes

[David M. Faguy]

Hello bionetland
I have a question about conserved amino acid changes. Basically is there
 agreement   on what can be considered   conserved changes? Most papers don't
define or reference what they call a conserved change. Any reference we can cite
would be   helpful. Thanks in advance.
David Faguy (faguyd at qucdn.queensu.ca)
Queen's University
Kingston, Ontario
Canada