When set to true, this property allows the page to be executed on a single-threaded apartment (STA) thread. This allows the page to call STA components, such as components developed with Visual Basic 6.0. Setting this property to true also allows the page to call COM+ components that require access to the unmanaged ASP built-in objects. These are accessible through the ASP ObjectContext object or the OnStartPage method.

In most circumstances, do not set this property in code. Set the aspcompat attribute to true using the @ Page directive in the .aspx file. When the page is requested, the dynamically generated class sets the property.