The heart of the MetaEdit+ environment is the Object Repository. In the multi-user version the repository is on the server, run there by a server process, and the clients accesses it via the network. In the single user version the repository is kept on the local hard disk.

All information in MetaEdit+ is stored in the Object Repository, including language definitions, diagrams, matrices, objects, properties, and even font selections. Hence, modification of system designs (or even modeling languages) in one tool or MetaEdit+ client is automatically reflected everywhere it appears, guaranteeing consistent and up to date information. Similarly, generators are based directly on the information stored in the repository. Only temporary data such as which windows are open and where, which varies between users and platforms and thus cannot be shared, is not stored.

The repository is stored as a set of directories and files within the main repository directory. As these files are highly interlinked make sure to treat the repository directory as an indivisible whole. If you need to carry out disk level operations (like copying) on the repository, they must always operate on the main directory and all below it – there are no files that can be individually copied or deleted within it. Changing or removing individual files or directories will damage the repository.