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.
DOT is a template file created by Microsoft Word, a word processing application. The DOT file provides a solution for situations where many similar documents with the same font and layout are required with simple changes between them needed, like names and places for example