Glycans cover all cell surfaces and interact with various molecules. Proteins that bind to glycans (lectins), viruses, antibodies, and microbes recognize some pattern of glycan structure, bind, trigger intracellular signals, or invade cells. To analyze these glycan recognition patterns, glycan array and lectin array technologies have been developed, and many glycan structures and lectins can be comprehensively analyzed. On the other hand, information technology is needed to analyze these many data and understand the pattern of glycan structures that are specifically recognized. Therefore, LiCoRR [1] was devised by information science experts dealing with glycan recognition data worldwide (Fig. 164.1). LiCoRR stands for Linear Code for Reaction Rules, and when it was first developed, it was proposed with the aim of standardizing substrate specificity in an informatics manner, targeting glycosyltransferases and glycosidases. LiCoRR can describe not only the glycan structure that the enzyme reacts with but also the conditions for the reaction. Therefore, it can be used for glycan biosynthesis simulation. On the other hand, it is thought that LiCoRR can be applied to molecules that recognize glycans, such as lectins, which are not enzymes. When using LiCoRR, one can compute the products that could be synthesized from a glycan structure that matches the substrate rules and keeps the constraints. However, to represent the recognition pattern of glycans by lectins, it is not necessary to represent the “product,” so the recognition pattern of the glycan structure can be represented using only by the substrate and constraint rules of LiCoRR.