Source code written in the Lex programming language (a standard lexical analyzer for Unix); may be processed with the lex utility included with most Unix distributions to generate a C program; the output is often written to a file named "lex.yy.c."
Program(s) that open x files
Windows: Flex for Windows; MKS Lex & Yacc; Editable with a text editor
Unix: lex; Editable with a text editor
Information from FileInfo.com - The File Extensions Resource.
http://www.fileinfo.com/extension/x
