Abstract: This invention concerns 2 Dimensional structure queries. Each structure comprises an array of nodes connected together by linkages to form one or more branches, or children, extending from a root, or reducing terminus. Each structure is represented using a sequence code generated to represent all the paths through the structure starring from the distal end, or leaf, of each branch and extending back to the root. The sequence code is governed by rules which guarantee there is a single unique representation for any structure. In particular one aspect of the invention concerns a database of 2 Dimensional structures, such as carbohydrate molecular structures. In another aspect the invention concerns a process for constructing such a database. Perhaps most importantly, in a further aspect the invention concerns a process for searching such a database to find all the structures that contain a given substructure within them.