In project mode, the format of the custom object library has been changed. In binary mode, there was a unique format applied to the object library which was a .4LI file. With project mode, a custom object library is instead another 4D project mode database, with each Project Form being a group of objects. As such, reusable templates can be built on a project database, and then that project database can be opened as an object library in future projects to reuse the preconfigured form objects to speed up development.

An example is creating a template for the navigational buttons of an input form. In project mode, there is a feature to quickly add in the fields for an input form, but the feature does not add navigational buttons. Creating a template for navigational buttons can be useful for this scenario.