OpenStructuredData
From OpenSimulator
Open Structured Data is a loosely typed data system, adding dynamic language facilities to strongly typed languages such as C#. Currently the OSD system is very similar to the Linden Lab Structured Data format, and supports all of the LLSD types and serialization formats. Additionally, JSON serialization is supported. Better native support for unsigned 64-bit integers and complex types such as vectors and quaternions is planned.
OSD is implemented in the OpenMetaverse.StructuredData.dll library that lives in the OpenMetaverse code repository. It relies on the data types found in OpenMetaverseTypes.dll, but has no additional dependencies.