Most objects (maps, structures, etc) have a dependency relationship with other objects. For example, a map depends on the structure(s) that define the input and output. These dependencies are managed automatically so that a change in a dependent object (the structure in the above example) would be reflected immediately in the map object, even without saving the structure object. The dependency management applies to all related objects, like structures that inherit from other structures, or a structure's use of a namespace container.
If, for example, you have a map editor open and one of the map's structures open in another editor and change and save the structure, when you switch back to the map editor it will detect the structure has changed and revalidate the map against the structure, reporting any problems encountered.
For performance reasons, the dependency information is tracked in separate metadata (so that it can be referenced without examining all possible objects). This metadata is automatically calculated and can be easily manually rebuilt if required.
Each object has a Used By and Uses menu item on the Repository navigator popup menu for the object. You can use these to discover the relationships between objects and quickly open the referenced object by double clicking on it in the dialog that appears.
Often you will change objects (mainly structures) and then you must validate and possibly change downstream dependent objects. For example, if you add a property to a Java class, you would reimport the Java classes and then you will need to open each of the maps that might use the structures that have changed to make sure the mapping information is correct and add new mappings as required.
To do this, you can use the Show Objects Needing Validation menu item in the Repository navigator popup menu for the project . Objects will show up as requiring validation until they have been opened and saved since the dependent object changed and have no warnings. So for example if you delete a property from a Java class and open the map that requires validation, if you don't remove the warning given in the map (by deleting the corresponding map element), then the map will still appear on the list of objects requiring validation.