The Open Data Description Language (OpenDDL) is a generic text-based language that is designed to store arbitrary data in a concise human-readable format.

The exact syntax of OpenDDL is described on the website openddl.org as well as in an appendix of the Open Game Engine Exchange Specification.

The declaration of a structure consists of an identifier followed by an optional name, an optional property list, and finally, the structure's contents enclosed in braces.

Another structure could then include a reference to this point by using the ref data type: OpenDDL defines the 15 primitive data types described in the following table.

Additionally, the floating-point types each have alternate long and short names.