The new tagged biblography export is very nice, but there is a routine (marked UGLY in the source) that causes processing to fail with otherwise-valid input. The failure message is ...eXt/tex/texmf-context/tex/context/base/mkiv/back-exp.lua:3889: invalid capture index stack traceback: [C]: in function 'gsub' ...eXt/tex/texmf-context/tex/context/base/mkiv/back-exp.lua:3889: in function <...eXt/tex/texmf-context/tex/context/base/mkiv/back-exp.lua:3747> (...tail calls...) and two URLs which cause this problem are: url = {http://www.jerwood-no.org.uk/pdf/Dunning%20Kruger.pdf}, url = {http://oll.libertyfund.org/?option=com_staticxt&staticfile=show.php\%3Fcollection=46&Itemid=27}, These URLs caused no problem with PDF output or in the previous exports, although they were not printed and exist only in the bibliography. Do I need to protect the special characters in the bib file, or is this a problem with the UGLY code? -- Rik