Computer Graphics Metafile (CGM) is free, platform-independent, international standard metafile format for storing and exchanging vector graphics (2D), raster graphics, and text. CGM uses an object-oriented approach and many function provisions for image production. CGM uses these object-oriented characteristics for remolding graphical elements to render an image. A metafile contains necessary information that defines other files. In CGM, a text-based source file contains all graphical elements that can be later compiled into a binary file.
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 CGM into many other file formats. Please see the complete list below.