You will define the business requirements relating to the input of information (e.g., where the information for the letter comes from), processing of the information (actual writing or typing of the letter), storage (where the letter is files) and output (what is the purpose of the letter, why is it important, who will use afterwards, what will it be used for).

During phase 1 the problems associated with the current system were identified, the policies and procedures were scrutinised, and the information was analysed.  During phase 2 the requirements of the new system must be defined, using the information that was gathered during phase 1.