[NTG-context] zero-width joiners etc

Dear gang, Does anyone here remember how to toggle Unicode control characters like the zero-width joiners, non-joiners etc? For example, some fonts map the control character to a symbol but we usually don't want that symbol showing up in normal text output. I know there is (used to be?) a switch in MkIV for toggling this but can't find it. (BTW: I miss the searchable mail archives on the ConTeXt Garden...) Thanks and Best Wishes Idris -- Professor Idris Samawi Hamid Department of Philosophy Colorado State University Fort Collins, CO 80523