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 file used for creating line plots in the form of vector images. They include text objects, splines, forms, arcs, lines and arrows. It can contain a set of colors, images and sketches. It was initially developed for the Xfig drawing program, but today it’s used in other drawing editors.