Notation
A notation is a system of marks, signs, symbols, or characters used to represent information in a consistent, shareable form. In software engineering, a notation gives a model or a piece of documentation a precise, agreed vocabulary, so that what one person draws or writes can be read unambiguously by another.
Notations range from plain prose and structured text — tables, bullet lists, numbered lists — to formal visual languages purpose-built for describing software and processes, such as UML for object-oriented design and BPMN for business processes.
Choosing a notation is a trade-off between expressiveness and how widely it’s understood. A rich, formal notation says more precisely but demands more of the reader, while prose is universally readable but harder to check for consistency.