While CHMTRN/PATRAN was not publicly documented at the beginning of the project, we received sufficient documentation material from the original providers of the transforms to be able to implement a parser and bytecode interpreter, augmented with additional, connected program logic in the chemoinformatics toolkit CACTVS (Xemistry GmbH, Glashütten, Germany) for at least a subset of these rules. Details of this work will be published elsewhere. We have now provided a description of the CHMTRN language. An important aspect of design and implementation of the CHMTRN/PATRAN parser and the SAVI algorithm based on it is that, as already-mentioned, the knowledgebase rules were all written for retrosynthetic application, whereas the SAVI project is forward-synthetic. Since we preserved compatibility of newly written transforms with the original retrosynthetic approach, this required a somewhat indirect traversal of the actual rule by first enumerating all possible reactant pairs (if dealing with a two-reactant transform), then testing in a first pass whether the "lhasa react" command in CACTVS produces a possible product, and only then subjecting this (tentative) product to the retrosynthetic analysis of the rule proper (including possibly encountering the above-mentioned ADD, SUBTRACT, or KILL clauses), executed by the "lhasa score" command. This workflow is shown in Figure : While CACTVS, in an initial transform compilation stage, parses the LHASA transforms written in CHMTRN/PATRAN, the algorithmic contents of the rules are then converted into internal, binary, data structures in CACTVS. The rules are therefore made available on the SAVI download page in both versions: human-readable source code (.src files), and compiled lhasa binary (.clb files).