Thanks for your continued help! I have solved the problem, with the help of (the presuppositions of) your questions and this: https://tex.stackexchange.com/questions/56525/natbib-setcitestyle-causes-undefined-control-sequence-error?rq=1.
Early in my exploring of Lyx a few weeks ago, I took advantage of the information offered by Maria Gouskova, who is in my field, at https://www.gouskova.com/resources/. That includes a link to her texmf directory with field-specific stuff in it, with an invitation to copy that into one's own texmf directory, which I did. That turns out to have included an out-of-date version of natbib.sty, which was the cause of my error messsages. Removing it solved the problem. Thanks again, David On Jun 20, 2017, at 11:23 PM, Richard Heck <rgh...@lyx.org<mailto:rgh...@lyx.org>> wrote: On 06/20/2017 06:25 PM, David Pesetsky wrote: Thank you for your detailed reply (and hello)! Your suggestion to add "comma" to [...]Class Options>Custom works very well, thank you! But no matter what I put after \setcitestyle (or where I locate the command in the document -- preamble, body), I get an error message from Lyx — for example: \setcitestyle {notesep={: }} The control sequence at the end of the top line of your error message was never \def'ed. If you have misspelled it (e.g., `\hobx'), type `I' and the correct spelling (e.g., `I\hbox'). Otherwise just continue, and I'll forget about whatever was undefined. It's not worth chasing down this problem to the ends of the earth, but if you have any troubleshooting suggestions, I'd be happy to try them. Very odd. The \setcitestyle command is defined by natbib.sty, and you said you were using natbib, yes? (It did not exist before version 8 of natbib, but that was about a decade ago.) What OS are you using? Do you know what LaTeX distribution you have? Actually, maybe a better questin is: What document class are you using? If you could produce as small a file as possible that causes this to happen and post that, then it will help debug the issue. Richard -- David Pesetsky [pese...@mit.edu<mailto:pese...@mit.edu>] Head, Department of Linguistics and Philosophy 32-D818 Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge, MA 02139 USA (617) 253-0957 office (617) 253-5017 fax http://web.mit.edu/linguistics/www/pesetsky.home.html