[phenixbb] reliability of the peptide from Coot

Dear All,   By Coot we can build a peptide according to 2Fo-Fc and Fo-Fc. For the most part of the peptide especially in the middle of the peptide, the reliability constructed should be very high. But at each end of the peptide, there are 1-2 residues constructed based on 2Fo-Fc contoured at lower sigma (even 0.8).   Will you please explain hot to analysis the reliability of the terminal reisudes constructed at each end of the peptide?   I am looking forward to getting a reply from you.   Cheers,   Fenghui