BGFX GLSL Shader Version?

[kappaOne]

I had a quick question about the BGFX Shaders as I could not find a clear explanation for the same, I understand that the shaders are pretty much identical to GLSL with a few difference as mentioned by the BGFX documentation.

However I wanted to know whether BGFX's flavour of GLSL follows a specific version of GLSL? or can you write them using any version of GLSL as you can with OpenGL.

For example, in modern GLSL there is no gl_FragColor variable in the fragment shaders, can you write BGFX fragment shaders without using the gl_FragColor variable as you do in modern GLSL or do you need to follow the classic GLSL style?