Hey folks, My book was compiling fine with the Jan 27th nightly, but kicks the bucket with the Feb 5th build: ! Undefined control sequence. <argument> \strc_descriptions_yes_reference \secondoftwoarguments #1#2->#2 \strc_descriptions_start_yes ...ons_yes_reference [#1] l.12 \startdefinition[definition:Albedo] {Albedo} ? E You want to edit file Source/Terms_and_Concepts/Terms_and_Concepts.tex at line 12 The offending line is just: \startdefinition[definition:Albedo]{Albedo} Hope that is helpful and my apologies if ConTeXt really is telling the truth and my typesetting is just bad. -- Kip Warner -- Software Engineer OpenPGP encrypted/signed mail preferred http://www.thevertigo.com