There are 8 file types use the .MDL file extension:
- MathWorks Simulink Model
- Half-Life Model File
- Warcraft 3 3D Model Text File
- Flight Simulator Airplane Model
- Rational Rose Model File
- DigiTrakker Module
- Lectra Modaris Clothing Design File
- Luigi's Mansion 3D Model File
1. MathWorks Simulink Model

- Developer MathWorks
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Popularity
- Category Data Files
- Format Text
An MDL file is a simulation model created using Simulink, a simulation and model-based design application. It contains the block diagram and block properties of a simulation.
MDL files are saved in a plain text format and typically include a list of objects. Each object contains a set of properties and values that are delimited by line breaks.
NOTE: The MDL format was replaced by the .SLX model format with the release of Simulink 2012.
You can open an MDL file in MathWorks Simulink. If you do not have MathWorks Simulink, you can open an MDL file using any text editor, including:
- Notepad++ (Windows)
- TextEdit (Mac)
- Atom
If you cannot open an MDL file in MathWorks Simulink, you can try changing the file's extension to SLX. This will usually allow you to open the file in Simulink.
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Updated: November 5, 2020
2. Half-Life Model File

- Developer Valve
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Popularity
- Category Game Files
- Format Binary
An MDL file is a three-dimensional model used for characters and creatures in the Half-Life video game. It is created using polygons and texture mapping for detail. MDL models can be seen from different views (wireframe, flatshaded, smoothshaded, and textured) using the Half-Life Model Viewer.
NOTE: QC files are actually used by Valve's Source game engine, so they are not restricted to Half-Life models.
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Updated: February 28, 2015
3. Warcraft 3 3D Model Text File

- Developer Blizzard Entertainment
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Popularity
- Category 3D Image Files
- Format Text
An MDL file is a model file used by Warcraft III, a real-time strategy game developed by Blizzard Entertainment. It stores a 3D model, including objects, meshes, and textures for buildings and units. MDL files allow text-based editing of model properties before generating a binary .MDX file used by Warcraft III.
MDL files use a nested structure to create model properties. For example, a material element may include a layer property which in turn defines a transparent property for the layer.
NOTE: MDL files are the text version of MDX 3D model binary files. They can be converted to the MDX format using the MDLX Converter program. From there, you can use several modeling tools to edit the model.
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Updated: August 30, 2010
4. Flight Simulator Airplane Model

- Developer N/A
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Popularity
- Category Misc Files
- Format N/A
An MDL file is a three-dimensional model of an airplane or other aircraft used by Microsoft Flight Simulator. MDL is a standard model format used by multiple versions of the Flight Simulator series.
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Updated: October 16, 2016
5. Rational Rose Model File

- Developer IBM
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Popularity
- Category Data Files
- Format N/A
An MDL file is a diagram or model created by Rational Rose software. It is used for modeling software architecture and design, and creating business models that improve predictability and productivity.
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Updated: April 12, 2007
6. DigiTrakker Module

- Developer N/A
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Popularity
- Category Audio Files
- Format N/A
An MDL file is an audio tracking module file used by the DigiTrakker music tracking program.
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Updated: June 23, 2016
7. Lectra Modaris Clothing Design File
An MDL file is a CAD file created by Lectra Modaris, a clothing design application. It saves the "cutter's must" list (or direction card) as well as the geometry for the pieces of the garment. MDL files are used for saving new fashion design's in men's, women's, and children's clothing.
When a design is complete, it can be sent to a machine cutter that cuts the designed patterns in a roll of fabric or another material.
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Updated: September 1, 2016
8. Luigi's Mansion 3D Model File

- Developer Nintendo
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Popularity
- Category Game Files
- Format Binary
An MDL file is a model file used by Luigi's Mansion, a Nintendo GameCube game. It stores 3D model data for characters, including Luigi, and objects that appear in the game.
Luigi's Mansion mainly uses the MDL format for its models but also uses the .BMD model format for some models in the game.
NOTE: The mdl2obj tool can open Luigi's Mansion MDL files and convert them into .OBJ files.
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Updated: March 28, 2015