Typically, the initial types include not only generic base types, but also some more specific types, with the generic types listed before the specific types to define a hierarchical chemical perception tree. Initial types provide an initial configuration for the simulation in the search space of types. The third is a file listing the SMARTS atom decorators which will be used during sampling (see examples in Table ). These three files are provided in a format where the first entry in each line is a complete SMARTS string or SMARTS decorator, and the second item is an informal name for the string or decorator. For example, "[#7] nitrogen" could be an entry in the initial type file, and "X4 connectivity-4" could be an entry in the decorator file. The other two input files relate to our specific test in this study, where we seek to determine how well sampled chemical perception trees can capture the typing of an existing force field (Section 2.1.1). Thus, our fourth input file provides the set of molecules to be typed in the process of evaluating a chemical perception tree, and the fifth contains the same molecules labeled with the atom types associated with the target force field.