This situation can only occur in alignments that ignore terminal gaps. Adjust the information by subtracting the indicated number of standard deviations expected from a random alignment from each position of the alignment. The normalization is based on the letter's relative prior probability when generating the alignment. For nucleic acids, this would typically be the genomic frequency of the bases or the frequency observed in the dataset used to generate the alignment. Complementary letters may use the same normalization number.
Any integer permitted by the machine is a permissible symbol.