ShaderLab includes a number of “fixed-function style” commands that allow you to write shadersA program that runs on the GPU. More info
See in Glossary without using any HLSL code.
Note: These commands are legacy, and are documented for backwards compatibility only. If your Shader object source file includes HLSL code, Unity ignores these commands completely. If your shader source file does not include HLSL code, Unity compiles these commands into regular shader programs on import.