The first check was to make sure ChemPer could generate SMIRKS on a very simplistic set of compounds. Specifically, we show that the SMIRKS we generate with ChemPer duplicate the typing of the AlkEthOH molecule set with smirnoff99Frosst version 1.0.7. AlkEthOH is a simple set of 42 molecules with only alkanes, ethers, and alcohols which was also used when testing SMARTY and SMIRKY. AlkEthOH has 5 bond, 7 angle, 16 proper torsion, and 9 nonbonded fragment types. As a side note, smirnoff99Frosst also includes improper torsion parameters, but AlkEthOH does not use these parameters as it only has single bonds between carbon, oxygen, and hydrogen. Fragments were clustered by which smirnoff99Frosst parameter they would be assigned. Then, these clusters were fed into SMIRKSifier to generate SMIRKS with all possible decorators based on this set of molecules (Section 3.4). In this test, the order of clusters were kept in the same order as their source parameters from smirnoff99Frosst.