Group commands with the Category block

Use the Category block to group commands that set the render state, so that you can “inherit” the grouped rendering state within the block.

For example, your ShaderA program that runs on the GPU. More info
See in Glossary object might have multiple SubShaders, each of which requires blending set to additive. You can use the Category block for that:

Shader "example" {
Category {
    Blend One One
    SubShader {
        // ...
    }
    SubShader {
        // ...
    }
    // ...
}
}

The Category block does not have an impact on shader performance; it is essentially the same as copy-pasting the code.