below details will help you to create BRD...
1) DataSources
2) Identifying Fact Tables
3) Identifying Dimension tables and their relation with Fact tables(Key fields) or get Data Dictionary
4) KPIs to be shown in Dashboard like Sales, Profit, Profit %, Discount, Gross Margin etc.
5) Filters to be displayed
6) List of Charts to be displayed
7) Getting the Cyclic and drill-down groups
Any rule based display of data (using Section Access)
9) Additional features like Export to Excel, Email etc.
10) Getting Mapping data in Flat files if not available in Databases
Also check this links too
Requirements Gathering | qlikcentral
Requirements Checklist | qlikcentral
Hope this helps you.
You Will get this thread from below link.
