.TOP File Extension

Data file created by Gromacs, a molecular data analysis application; contains a molecular topology, which formally describes the structure of a molecule; created by pdb2gmx, a program that generates topologies from Protein Data Bank (.PDB) and Residue Topology Parameter (.RTP) files.

A TOP file may also be a CAD file created by TopSolid, a program used for CAD design and PDM (product data management). It contains a CAD drawing, which is comprised of one or more parts. Each TOP file includes the 3D geometry of the part models and may include Bill of Materials (BoM) information as well.