This is a vector imaging format used in the CorelDRAW editor. It has a template that can be applied for other designs, including styles, grid parameters, page layout and other parameters. The CDT template allows for the creation of several images in one style without changing the settings in manual mode.
The PNM file type is primarily associated with PBM Portable Any Map Graphic. A family of formats. The files are usually .PNM but can have the form .P?M with ? being any letter.