The application programming interface permits an application to specify resources to be used by shaders, executed by the GPU, through a data structure called the “root arguments.” A root signature is a data structure in an application that defines the layout of the root arguments used by an application. The root arguments are a data structure resulting from the application populating locations in memory according to the root signature. The root arguments can include one or more constant values or other state information, and/or one or more pointers to memory locations which can contain descriptors, and/or one or more descriptor tables. Thus, the root arguments can support multiple levels of indirection through which a GPU can identify resources that are available for shaders to access.