[1] GEMS helps developers rapidly create a graphical modeling tool from a visual language description or metamodel without any coding in third-generation languages.
Graphical modeling tools created with GEMS automatically support complex capabilities, such as remote updating and querying, template creation, styling with Cascading Style Sheets (CSS), and model linking.
The built-in metamodeling language is based on the UML class diagram notation.
Metamodel constraints can be specified in declarative languages (e.g. OCL, Prolog) or, alternatively, in Java.
GEMS extension points can be used to create an interpreter which traverses the domain-specific model and generates code.