OSL

OSL stands for Open Shading Language and allows to write your own shader descriptions, that can be shared between other renderers that also offer OSL support. OSL scripts can be loaded as files or written directly inside the shader dialog.

You can find out more about OSL on this website: https://github.com/AcademySoftwareFoundation/OpenShadingLanguage and some Redshift compatible OSL shaders here: https://github.com/redshift3d/RedshiftOSLShaders