There are two different approaches to solve this problem, which correspond to the two main softwares used in the field: ToposPro and Systre . ToposPro is a crystallographic tool that allows to retrieve an extensive set of topological properties from crystals. It is a proprietary software, but its topology detection tool can be accessed for free online for crystallographic files in CIF format . Its strategy to identify the topology of a net consists in computing three specific properties for each vertex u: