Found this after some searches:https://en.wikipedia.org/wiki/ISO_10303http://docs.mcneel.com/rhino/5/help/e... ==Rajeev JainSoftware Development Specialist1134, Building 240Mathematics and Computer Science DivisionArgonne National LaboratoryArgonne IL, 60439, USAO: 630-252-3176Google: rajeeja, Voice: 312-725-3380== On Tuesday, August 25, 2015 11:55 AM, "Vander Zee, Evan B." <[email protected]> wrote: Do you know the source of the file itaps/brick_2.stp in the CGM repository? It looks to me like the edges in the file have improper edge orientations. I have some local changes to CGM that, I thought, fix the face-to-volume sense bug. I am testing the changes in various ways and learning more about OCC and CGM. This version of itaps/brick_2.stp has been used by the test_edge_orient test in the itaps directory. I disabled the test previously in my edgeFaceSense branch when I fixed an edge-to-face orientation problem. I am working on rewriting the test now so that it properly tests the face-to-volume sense and the edge-to-face sense for both OCC and ACIS. I have the face-to-volume part of the test working fine for OCC now, but my revised edge orientation part of the test is failing. This part of the test tests edge orientation after reading the itaps/brick_2.stp file. When I create a 2 x 2 x 2 brick using iGeom_createBrick rather than reading the brick from file, my revised edge orientation part of the test passes. If I save that brick to a file, then I can also read the file I've saved, and the edge orientation part of the test passes. I looked at the brick_2.stp file and my human-readable interpretation is that the edge orientations are encoded incorrectly. I think I could correct it by hand within the file by changing the orientation of some of the oriented edges at entities 106 through 144. I want to know whether it's okay to do that or the STEP file came from some source outside of CGM that we need to be able to support. The brick that CGM writes out after iGeom_createBrick is represented quite differently from the way the one in itaps/brick_2.stp is represented. It would help me if I could get a reference for the geometric STEP entities. I have pieced together a few things through Internet searches, but I have not been able to find good reference documentation for the parts of STEP that are used by CGM. Do you know of any? -Evan [email protected]