In MkII, one could configure the index to have different types of page entries, e.g. roman and italic, by using \setupregister, as in the example at http://wiki.contextgarden.net/Command/setupregister. That doesn't work with a fairly recent MkIV (2014.05.17 beta). I see that it's a long-standing feature request: http://www.mail-archive.com/ntg-context%40ntg.nl/msg67495.html So, it is probably not on the short-term feature list. But, if it is on the list, please let me know, as I'll keep using it for my textbook! Otherwise, I'll just make all the page entries the same style. The perfect is the enemy of the good, especially after 19 years... (Right now with 2014.05.17 beta, using the feature, say as \index[definition::]{commutativity}commutativity, gives an entry alphabetized according to the "definition::" key.) Regards, -Sanjoy