XLL+ maintains a model of an add-in function. The model is run against a selected code template to generate and regenerate the code for the add-in functions. The model can be edited using the XLL+ user interface tools: the XLL+ Function Wizard and the XLL+ ToolWindow.

The model is saved as one of the arguments of the IMPLEMENT_XLLFN3 macro. It is loaded from there by the XLL+ ToolWindow and XLL+ Function Wizard.

The model can be exported as XML, and is used in that form by the help generator.

The objects of the model are listed below.

Object	Description
Settings	This object contains properties which apply at a system-wide level. These settings apply to all projects, and to all add-in functions within each project. Settings can be edited using the XLL+/General page of the Visual Studio Options dialog.
Function	This object represents a single add-in function, including its signature, arguments, description and features.
Argument	A single argument to an add-in function
Group	An argument to an add-in function that contains multiple inner arguments.
Bound	The constraints and behavior of a single dimension of a vector or matrix argument.