This is a format created in the Acorn Draw program, intended for image visualization by using vector lines. It’s used for storing information in the publishing business (brochures, logotypes, etc.). The main advantage is it’s high quality source images when printing. It’s been in use since 1980.
This is a vector images format created in a program for SK1 drawings, which was developed under Linux for open distribution. It contains vector graphics and is used for storing maps, brochures, logos and other illustrations. Today it’s used in vector graphics editors such as Sketch and Skencil.