Hello all, The \tl_tail:w function is deprecated and will be removed from expl3 after 2012-12-31. The background here is that as implemented in the current release, \tl_tail:n will strip the braces in output such as \tl_tail:n { a { b } } but not \tl_tail:n { a { b } { c } } An upcoming CTAN release will fix the behaviour of \tl_tail:n such that braces will never be removed (the 'tail' will be 'what is left after \tl_head:n has acted'). However, this cannot be fixed in \tl_tail:w, and so we are removing it as documented. The recommended replacement is \use_none:n <tokens to have head removed> with either inside a \tl_if_blank:nF test or the use of an empty group \use_none:nn <tokens to have head removed> { } Also note that \tl_tail:n will prevent expansion of the result inside a x-type expansion \tl_set:Nx { \tl_tail:n { <tokens> } } and expands correctly inside an f-type expansion \tl_set:Nf { \tl_tail:n { <tokens> } } and so the functionality of \tl_tail:w is very rarely required. -- Joseph Wright