Played Seafarers/Cities and Knights recently with someone new and they insisted that a gold field would allow a city to draw a resource and a commodity. I may have missed something, but I checked my rules and the FAQ and didn't find anything specific.
His reasoning was that in C&K a city can produce commodities, so naturally a gold field would allow you to get one as well. Additionally, that the rules say a city can't choose to take two resources instead of a resource and a commodity (for a city that produces a commodity) so the ability to take two wood/ore/sheep would also be against the rules.
My reasoning was that the Seafarers rules specifically mention resources only and the rules for combining the two make no mention of any changes, so the Seafarers rules should apply.
While we settled this amicably (after all, we play to have fun), for future reference, who was right?