MDL file format (MSFS)
From FSDeveloper Wiki
MDL sections
MSFS uses glTF files for models, but when these are combined to BGL file for use in scenery they are still wrapped as MDL files. These MDL files have a similar RIFF container structure as FSX MDL files. The table below shows the different sections and their content.
TODO add table
glTF standard exceptions
Although the glTF files are stored in binary form inside the MDL files, there are a number of optimizations that the MSFS package tool performs that makes them deviate from the glTF standard. The list below gives an overview of these differences.
TODO add list