New nomenclature adopted to include protonated and unprotonated residues: 0YN - Alpha-D-Glucosamine (Alpha-D-GlcNH2) 0Yn - Beta-D-Glucosamine (Beta-D-GlcNH2) 0YNP - Protonated Alpha-D-Glucosamine (Alpha-D-GlcNH3+) 0YnP - Protonated Beta-D-Glucosamine (Beta-D-GlcNH3+) The first character specifies linkage position. The second character specifies the GLYCAM residue name in accordance with the GLYCAM one-letter code. The N/n third character is used here to indicate that instead of acetyl group as indicated by the letter Y, this residue is Glucosamine. The upper and lower case indicate alpha and beta. The fourth character has been included to allow naming the protonated residues.