[NTG-context] defining bug not setting up blank spaces

Dear list, I have the following sample: \defineblank[ab][none] \starttext \defineblank[ab][big] a \blank[ab] b \stoptext Am I missing something or is there a reason to force the new definition (instead of the setup) of already defined blank spaces? I mean, if this isn’t a bug, I don’t see the gain in this behavior. Many thanks for your help, Pablo -- http://www.ousia.tk