Events important to the family as a whole, to individuals within it, might form part of the key, along with informal rules for making changes.

There are several informal rules governing fighting in ice hockey that players rarely discuss but take quite seriously.

There are a number of informal rules that dictate how dancers should choose their dancing partners.

It also meant coexisting with the occupiers, for which informal rules were drawn up.

Many other states have formal or informal rules to discourage use of the test by insurance companies.

Within a few months the corporation offered to make an exception to their informal rule that no one younger than 21 could buy a franchise.

Group norms are the informal rules that groups adopt to regulate members' behaviour.

There may be formal or informal rules about the number of bookings allowed per month.

Each session has its own informal rules as to which instruments are acceptable and in what number.

She said the informal rule, which is not a companywide policy, had been in effect at that office for more than a decade.