All the embedded ISF files are present inside of the Standard Pack
You can re-arrange the folders as you want to organize your own ISF shaders.
To add new ISF generator files in your library, add a ISFGenerator folder inside of your medias directories.
You can also code the ISF shader directly inside of the Shader Editor
Press [Ctrl]+ [Enter] at any time in order to compile the shader.
Go check ISF Modifier
for the other side of the mirror.
The ISF website: www.interactiveshaderformat.com
More info on the ISF format: http://vdmx.vidvox.net/blog/isf