There should be a naming convention for local variables for result values, for values to be returned from a function, which are not just success/error results such as nsresult or bool typed results.

Options include:

• res as a generic name
• result as a generic name
• non-generic names that are dependent on the context

rv and ok are reserved for nsresult resp. bool values by the global coding style.

This has been discussed in https://phabricator.services.mozilla.com/D77452#inline-454098, e.g.