The program can be run interactively, but it is usually more efficient to run it from a script. There is a global workspace in memory, and the commands act on variables in it. The global workspace is fixed; new variables cannot be created, as in more sophisticated interactive programs. Furthermore, the variables which are present are of fixed dimension which can only be changed by recompilation. This is intended to be changed in the future, but for now the dimensions are large enough to handle most data. See Global Workspace for a discussion of the variables available.
The commands come in two categories, read/write operations and action commands. The read or write specification consists of a file name and a format name. The file name refers to the file to read or write to, and the format name refers to the particular section of the global workspace to be modified. For example, on read, the format name, orientations, will modify the number of orientations, the actual orienation matrices, the weights and hardnesses associated with each orientation. An action command will produce some internal action on the global workspace. It could be as simple as resetting a single variable, as is the case with various output options, or it could be a very complex operation such as evolving the texture in time according to a specified deformation. Below are a list of commands and a list of file formats.