Upvote:2
The code itself has no standard structure, except the first letter which is the booking class (used to determine availability buckets and service levels), each airline make up their own codes which may or may not have a structure.
For instance the 7
probably means there’s either a 7-day minimum stay (for a return fare) or a 7-day minimum advance purchase, but it could mean anything else they want.
You have to lookup the specific fare code for that specific airline to find out the rules.
Usually the simplest option for passengers is just to check their receipt/confirmation or e-ticket, or to log into the “manage my booking” section of the airline’s website.
Otherwise you can use a tool such as Expertflyer to look up fare rules (it’s a subscription-based service but there’s a free trial). Note that fare rules in standard GDS format are not always very easy to understand and can easily be misinterpreted if you are not used to them.