MdL

MDL is an acronym with multiple meanings across different fields. Notable uses include the Material Definition Language for describing physically based materials, the Minimum Description Length principle in statistics and information theory, and the historical Model Description Language associated with Simulink models. Each sense reflects a distinct concept in computation, modeling, or rendering.

Material Definition Language (MDL) is a high-level shading language developed to describe materials in a renderer‑independent way. It enables artists to define materials as graphs of functions, textures, and parameterized closures. An MDL material can be shared and repurposed across different rendering engines and content creation tools via an MDL software development kit. MDL supports features commonly needed in physically based rendering, such as various BRDFs, clear coats, layered materials, and anisotropy, with the aim of promoting consistency and portability of material assets across workflows.

Minimum Description Length (MDL) is an information-theoretic model selection principle introduced by Rissanen. It frames model selection as an optimization problem that minimizes the total description length of the model and the data given the model. By balancing model complexity against data fit, MDL provides a criterion for choosing among competing models and configuring model parameters. Variants of the approach, such as two-part MDL and refined MDL, appear in statistical literature and have applications in machine learning, data compression, and predictive modeling.

Model Description Language (MDL) refers to the legacy text-based format used by MATLAB/Simulink to store models, typically with the .mdl extension. MDL files encode block diagrams, components, connections, and parameters in a human‑readable form. Beginning with newer versions of Simulink, the .slx format has superseded .mdl, but MDL-based models remain in use for compatibility with older systems and workflows.