Generally speaking, a data format is a serialization of a data structure. Often, "data format" refers to a text-based file format, but sometimes, can refer to a set of indexed data files such as a database. It may also refer to a serialization as part of a wikipedia:wire protocol.
There are many data formats that are key for interoperability for a good interoperable PIM/CRM/wiki/notetaking system/task management system. There are the pieces that the obvious components (because many systems support them already):
- Simple textual data serializations:
- Plain text serializations of rich text