Suppose we are writing an enhanced entity-relationship diagram (EERD) for a company's database. This company offers two services A and B. If the two services were disjoint, then this might look something like:
In many cases you could request both services from the company, in which case we would use an "o" instead of a "d".
A person cannot request service B by itself. A person can request services as often as they want. But it's highly unlikely anyone would request services more than once every 10 years or so.
Suppose that for this company, you can either request service A and B together, or service A only. What is a good way to describe this constraint succinctly in the diagram?