Tags and keywords
There is a supplier Requirement with text:
'The home entertainment system should annoy the neighbours as much as possible.'
There is a derived client Requirement with text:
'The sound system shall have a volume control that goes all the way to 11'.
The poor neighbours; clearly this home entertainment system is being developed by some backpackers in a "party house" flat in Bondi, Australia.
Note how the client requirement, the derived one, is of a different nature from the supplier requirement, the one it is derived from. It operates in a different solution space, it involves a specific part of the larger system, and it is far more specific. Derived requirements are often part of a solution that helps address higher level requirements.
The diagram shows Note callout style. We'll see next some other ways of indicating this information directly on the Requirements symbols.