Which meta-information for files getting timestamped do we store
All infos are optional, but in my prevalent-implementation i required that any three options had to be specified, but no specific one was required.
These are of course additional to the hash-values, which are required :)
Please see the Open Source as Prior Art project page.
In 1999 the USPTO issued this RFC: http://www.uspto.gov/web/offices/com/sol/notices/priorart.htm