From Seo Wiki - Search Engine Optimization and Programming Languages
Setext is a lightweight markup language originally designed by Ian Feldman with input from TidBITS publisher Adam C. Engst for use in simple email and USENET exchanges. It is intended to remain readable as plain text even by people who do not know that the text contains markup. Setext was used for many years as the email format for TidBITS and was one of the influences on the development of Markdown.
This is not an exhaustive listing of Setext syntax.
First-level heading =================== Second-level heading -------------------- ~emphasis~ (e.g., italics) **strong emphasis** (e.g., boldface) _underline_ * bullet point hyperlink_