FileInfo.com - The File Extensions Resource

.ETX File Extension

File Type	Structure Enhanced Text (Setext) File
File Format	File
Common?	No
File Description	ASCII text file format known as "Setext" that is used to distribute information over the Internet; can be opened with EasyView or another Setext viewer; may also be readable with a basic text editor, though the text formatting will be lost.
Program(s) that open etx files	Mac / Windows: EasyView

Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/etx