<P> One possible use of a process model is to prescribe how things must / should / could be done in contrast to the process itself which is really what happens . A process model is roughly an anticipation of what the process will look like . What the process shall be will be determined during actual system development . </P> <P> Conceptual models of human activity systems are used in soft systems methodology (SSM), which is a method of systems analysis concerned with the structuring of problems in management . These models are models of concepts; the authors specifically state that they are not intended to represent a state of affairs in the physical world . They are also used in information requirements analysis (IRA) which is a variant of SSM developed for information system design and software engineering . </P> <P> Logico - linguistic modeling is another variant of SSM that uses conceptual models . However, this method combines models of concepts with models of putative real world objects and events . It is a graphical representation of modal logic in which modal operators are used to distinguish statement about concepts from statements about real world objects and events . </P> <P> In software engineering, an entity - relationship model (ERM) is an abstract and conceptual representation of data . Entity - relationship modeling is a database modeling method, used to produce a type of conceptual schema or semantic data model of a system, often a relational database, and its requirements in a top - down fashion . Diagrams created by this process are called entity - relationship diagrams, ER diagrams, or ERDs . </P>

4. what is a physical or mental representation of an object or an event