Add-In Files

An add-in is essentially an Excel workbook file with a few important differences:

• The workbook's IsAddin property is True - which means that it can be loaded and unloaded by using the Add-Ins dialog box. Access this dialog box by choosing Office Excel Options. Click the Add-Ins tab, select Excel Add-Ins from the Manage list, and click Go.

• The workbook is hidden and cannot be unhidden by the user . Consequently, an add-in is never the active workbook.

• When using VBA, the workbook is not part of the Workbooks collection.

Many add-ins provide new features or functions to Excel. You can access these new features as if they were built into the product.

You can create your own add-ins from workbook files. In fact, creating add-ins is the preferred method of distributing some types of Excel applications. Excel 2007 add-ins have an XLAM extension by default.

Note  

Besides XLAM add-ins, Excel supports XLL add-ins and COM add-ins. These types of add-ins are created using software other than Excel. This book discusses only XLAM add-ins.

CROSS-REFERENCE  

Chapter 21 covers the topic of add-ins in detail.