Investigating such questions helps to uncover the business rules that apply to the
processes. In the example above, the business rules might be age related, as
suggested – perhaps this is an event with a lower age limit of 18 years. Another
potential eligibility rule could be that when there is a group booking there has
to be at least one person over 21 years old. Alternatively, there could be a
prerequisite – for example, to attend a radio show a person might have to submit
questions in advance in order to gain attendance information. Examining the
transitions between tasks and steps will help to uncover the tacit knowledge
about the business rules.
Business rules and modelling data
Business rules do not just impact upon the business process analysis – they
are also key to understanding how the data in the organisation needs to be
organised. When modelling data, the business rules govern aspects such as
which items of data can be grouped together because they are in one-to-one
correspondence, and the ways in which these data groups are associated with each
other – for example, is there an association between two data groups, and, if so,
what are the rules that govern it? If we consider the ticket example above, in many
ticket booking systems the number of tickets associated with one customer is
limited to a maximum number. In this situation, the business rules could state that
a customer must hold a minimum of one ticket and a maximum of four tickets.
Data modelling, the business rules shown within data models, and techniques
for modelling data are explored in further detail in Chapter 6, ‘Define
requirements’.