[NTG-context] \definecharacter

Hi all, is the command \definecharacter deprecated in mkiv? Some of my environments stopped working. Minimal example: %\definecharacter mytest \char"00F8 \define\mytest{\getglyph{name:lmroman10book}{\char"00F8}} \starttext Hello w\mytest rld! \stoptext I expected lines 1 and 2 to work, but line 1 gives an error ("Undefined control sequence"). So: is this command no longer available in mkiv? All best Thomas