One of Agile Modeling's (AM) practices (discussed in Chapter 17) is Apply Modeling Standards, the modeling version of Extreme Programming (XP)'s Coding Standards (Beck 2000). Developers should agree to and follow a common set of standards and guidelines on a software project, and some of those guidelines should apply to modeling. Models depicted with a common notation and that follow effective style guidelines are easier to understand and to maintain. These models will improve communication internally within your team and externally to your partners and customers, thereby reducing the opportunities for costly misunderstandings. Modeling guidelines will also save you time by limiting the number of stylistic choices you face, allowing you to focus on your actual job – to develop software.

When you adopt modeling standards and guidelines within your organization, your first step is to settle on a common notation. The Unified Modeling Language (UML) (Object Management Group 2004) is a good start because it defines the notation and semantics for common object-oriented models. Some projects will require more types of models than the UML describes, as I show in The Object Primer 3/e (Ambler 2004), but the UML will form the core of any modern modeling effort.

Your second step is to identify modeling style guidelines to help you to create consistent and clean-looking diagrams.