Dirk Hagedorn, the UDO "founder", reports:
It was autumn 1994 when I wrote some little programs for which I needed an ASCII manual, an online help and a printed documentation. In all cases I began writing the ASCII manual. In a copy of it I inserted hypertext commands. Finally the ASCII manual was imported into a text processor, layouted and printed. It didn't take a long time for me to recognize that this was an inefficient work: if there were any changes in one of the files both the others had to be changed in the same way. And if there were lots of changes it was necessary to start the whole procedure right from the beginning. When I finished these manuals I said to myself:Oh no, Dirk, there must be another and easier way to get different versions of one text file!. January 1995 I started to think about a new text format with the project nameUDO(as the abbreviation for Universal DOcument). The UDO syntax should be easy to learn and flexible enough and so I decided to create a syntax like LaTeX. Next to this I began writing the software that was able to convert this new text format into ASCII, ST-Guide and LaTeX: UDO was born! At this time UDO was really a small program with only some features. The syntax contained about 10 commands and the source code was about 10 kB large. Nevertheless this small hack was of a great help for myself and the upper described horror scenario was history. Since this time UDO has been growing up day by day. UDO now supports many different text formats, it offers a large variety of layouting commands, it is available for different operating system and the size of its source code and documentation is now a hundred times larger than it was in former days. UDO has become to an operating system independent, very powerful and — proverbially said — universal tool.
UDO ist Open Source since October 27, 2001.