This shader gets ICE attributes of the Integer data type created for particles in the ICE tree. To use this shader, you must make sure that the particles first have the appropriate attribute created for it in its ICE tree.
For general information, see Bringing ICE Data into the Render Tree with Attribute Shaders.
Plugs into any port on a shader that supports Integer data, such as the input ports on the Particle Gradient shader. For example, you could drive the gradient color based on custom particle attribute that you've created and brought into the render tree with an Integer Attribute shader.
When you plug this shader into ports that only accept scalar values, an Integer to Scalar converter node is automatically created to convert the values.
