According to http://wiki.contextgarden.net/Registers#Processors, processors are the MkIV way of highlighting within index entries. If there are highlighted and not-highlighted entries, the normal version wins. If there is a highlighted version with subentry, the subentry becomes highlighted and is sorted unter the normal main entry, if there doesn’t exist a normal entry with the same subentry. (These are just observations, I wouldn’t know how it should be different.) But: Is there a way to highlight just subentries? e.g. \index{Sun+emph->rays} """ \defineprocessor[emph][style=italic] \starttext \index{Sun} \index{Sun->rays} \index{emph->Sun} \index{Sun+emph->rays} % doesn’t work \index{emph->Sun+rays} % rays upright \index{emph->Sun+beams} % beams italic \placeindex[n=1] \stoptext """ Greetlings, Hraban --- https://www.fiee.net http://wiki.contextgarden.net https://www.dreiviertelhaus.de GPG Key ID 1C9B22FD