I have written various user stories that describe functionality at a pretty high-level. For example:
As an analyst, I want to view the current share price, so that I have quick access to an up-to-date valuation of stock across the Euronext, London and New York stock exchanges.
This requirement is based on existing functionality that is being re-developed in a new version of some software. I can see from the existing implementation that the actual information displayed includes a lot of extra data such as different classes or shares, different timescales of graphs etc.
I think it is impractical to capture all the functionality in the current implementation. So I have two questions:
How do I decide an appropriate level of detail for the requirement that is basically 'do what the current piece of functionality does'.
Is there some structured approach of accompanying the user story with more information? At the moment, I feel this would be the job of wireframes.