Chirok: a post-refinement tool to analyse absolute structure

Chirok is software for a post-refinement test of the absolute structure. The software allows a user to calculate a distribution of the measure of chirality based on intensity quotients and linked to the Flack parameter. The distribution is fitted by a set of peak functions, the refined centre of which gives an estimate of the Flack parameter with the same or better precision compared with the usual refinement schemes. The use of this software is illustrated with a collection of published data for chiral structures.