MDDL: The Math Data Description Language and MathHub data hosting.

The MDDL allows mathematical data set creators to describe the meaning of mathematical objects in a data set and their database encoding declaratively and then generate data tables, user interfaces, and update facilities from them. MDDL uses

• object theories that specify the mathematical types of objects
• data base theories that specify database types,
• codecs (encoders/decode pairs) that mediate between them, and finally
• schema theories that bind all of them together, and provide metadata-based hints for infrastruture generation.

All of these are regular flexiformal theories, that can make use of the existing MathHub libraries. Consequently, a mathematical data colletions are regular MathHub Library with MDDL schema theories.

• MDDL archives for the schema theories. The main one is usually just called mddl.
• VT archives for the virtual theories generated from the mddl archive, the main one is usually called vt

An example of a MDDL-based schema collection can be seen in MathHub (MDDL, VT, and the generated data collection Symmetric Objects)