Joseph, > The bug as I see it is that here the code not only removes the space but > also the brace group around a single token. I assume you'd get the same with > > [ word {a} word ] => 'wordaword' not 'word{a}word' > > which isn't as far as I know detailed. yes i guess you get that, and no there is no explicit formal statement that the above would be the case nor is there a statement that [ \section ] is not a valid input in this case. [ And yes, there have been people who complained that \footnote{\chapter{foo}} doesn't work and that this is not documented, and no I don't think we will document it] Instead the specification of \usepackage [optionlist] is that optionlist is a list of named options separated with comma and optional spaces around the comma. And what is acceptable as a "name" in LaTeX is fairly well defined though again not too formal and yes, therefore this also has boundary cases (often producing problems if you have language specifics like ":" being an active char making names for labels blow etc) Option names have no spaces and no braces and so the result of passing such stuff is undefined (well not undefined as the behavior is deterministic, but there can be "surprising" behaviour for boundary cases). So the result of undefined usage doesn't classify as a bug. So all i nall I don't think it is a bug but it is an extended usage of an interface for something it wasn't intended for so that the boundary cases are a bit surprising, ie "optionlist" will be processed so that all spaces within are removed and that brace groups that are surounded at the outside by spaces (or the beginning or end of optionlist) get the braces removed oh well. not sure I got that fully right :-) but ... frank