A file with .igs (Initial Graphics Exchange) extension is a 2D-3D design exchange file format that is independent of source or destination file format specifications used by CAD applications. It is used to exchange design information about circuit diagrams, wireframes, the freeform surfaces between two independent systems. IGS files can be opened by applications such as Autodesk, FreeCAD, CADEX CAD Exchanger, and other similar applications.
Files with PPTM extension are Macro-enabled Presentation files that are created with Microsoft PowerPoint 2007 or higher versions. They are similar to PPTX files with the difference that the lateral can't execute macros though they can contain macros. PPTM files can be edited by opening them in Microsoft PowerPoint and updating the contents. Another similar format is PPSM but it is read-only by default and starts the slideshow when opened. PPTM, like PPTX, contains slides for different presentation elements like text, images, videos, graphs and other related material.
You can also convert IGS into many other file formats. Please see the complete list below.