A POTM file is a macro-enabled presentation template created by Microsoft PowerPoint, a program used for creating slide show presentations. It contains default images, slide templates, macros, and formatting. POTM files are used to create multiple .PPTM files with the same formatting and macro settings.
PBM is a Portable image in black and white. Can be opened with programs: Adobe Photoshop CS, ACD Systems Canvas 15, ACD Systems ACDSee 17, Newera Graphics Converter Pro, Corel PaintShop Pro X6. File contains 1 bit per pixel. PBM is a kind of file format PPM. And can be readable or binary.