Here we are concerned only with the requirements that relate specifically to the data. Establishing requirements involves consultation with, and agreement among, all the users as to what persistent data they want to store along with an agreement as to the meaning and interpretation of the data elements. The data administrator plays a key role in this process as they overview the business, legal and ethical issues within the organisation that impact on the data requirements.
The data requirements document is used to agree requirements with users. To make sure that it is easily understood, it should not be overly formal or highly encoded. The document should give a concise summry of all users' requirements – not just a collection of individuals' requirements – as the intention is to develop a single shared database.
Below is an example of a statement from an Open University summary database card:
Each course which is available for study is given a course code, a title and a value for credit points – either a 30-point course or a 60-point course. A course may have a quota – the maximum number of students that can be enrolled on the course in any one year; each quota is reviewed regularly and the last date of review is recorded with the quota. A course need not (yet) have any students enrolled on it. Students may not enrol for more than 180 points’ worth of courses at any one time.
You should note that the above says nothing about how the data are processed, but it does state what the data items are, what attributes they have, what constraints apply and the relationships that hold between the data items.