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Chapter 15 - Customizing SysML for Speci... > 15.2 Defining Model Libraries to Pro... - Pg. 373

15.2 Defining Model Libraries to Provide Reusable Constructs 373 allow the language defined by the original metamodel to be augmented with concepts for domains not covered directly by SysML. Model libraries can contain model elements that are described by met- aclasses in the metamodel, or concepts that have been further extended in a domain-specific profile. Modeling tools are normally engineered to support a specific metamodel and will only understand models that use that metamodel. Extending the language by adding to the metamodel is something typically done by a tool vendor. The benefit of a profile is that many UML tools are engineered to support not just the core metamodel, but also any user-defined profiles. This means that a profile for a specific domain can be loaded into a UML tool and the tool will understand how to store, display, and edit elements of that profile without the need for a tool extension. So, a modeler can make use of a set of modeling elements for a specialized modeling domain without needing to change the modeling tool, and can exchange the user defined model between modeling tools that support the profile. As discussed in Chapter 5, SysML is based very closely on a subset of the concepts in UML, so it is defined as a UML profile. This allows UML tools to support SysML simply by loading the SysML profile, although many UML tool vendors have extended their UML tools to make the SysML profile more usable. The rest of this chapter discusses model libraries and profiles in detail. Section 15.2 describes model libraries and their use in defining reusable components. Sections 15.3 and 15.4 cover the definition of stereotypes and the use of profiles to describe a set of stereotypes and supporting definitions. Sections