Problem
I need to add additional information that supports a requirement statement, but is not itself considered a deliverable.
Solution
Apply a strict formatting convention that all inline supporting notes are displayed in italics, preferably in a separate paragraph to the requirement statement, where possible.
Example
Creelcard must not assume or require a current network connection for the core functions of catch information capture at a Fishing Location.
It can be expected that many geographic locations in which Creelcard will be used on-site will have no / inadequate network coverage to access internet services (maps etc).
Discussion
A key recommendation is to ensure individual requirement statements are atomic, clear and concise; the statement itself should include nothing but the actual requirement. However, it is often a good idea to add additional notes (references, sources, notes) that supplement the statement, placed as close as possible to the requirement statement itself.
Having authored a draft statement, critically ask "Does this paragraph contain anything that is not of the requirement itself, or relates to, or supports the statement?". Separate out supporting information in a separate paragraph (better), or place commentary in brackets in-lined in the statement itself; in both cases using italics to indicate the text is not to be included in the requirement itself. Adopting this discipline is another way to help achieve the goal of writing unambiguous, concise statements of requirement.