Restaurants are getting hyper-specific communicating with guests when it comes to food allergies. You probably have a training program in place. But your first contact with the guest can ensure everyone is on the same page.
What questions should you ask your guests via e-mail or at the table?
I like it when a restaurant works down this list, asking first about allergies, then intolerances and finally aversions.
Allergy - Potentially fatal or could cause shock symptoms, swelling of the airway or other symptoms. Cross contamination could be a concern. Ask your guest specifically if there will be issues if any ingredients mix.
Intolerance - Not an allergy. Could cause digestive complications such as diarrhea, vomiting or reflux.
Aversion - The guest doesn't like it.
I've seen too many muddled conversations where it's like a game of charades.
The clearer you are with your guest, the clearer they'll be with you. If your people on the floor are uncertain about the guests' needs, be polite and patient with them. It's OK to say "I'm sorry, but we can't do that." No one ever got upset because they were cared for too much.
A US-based resource can be found here.
These two US companies operate in the training space:
Other regions of the world have different standards and training, but there are ample resources available online.