The controls element defines a collection of register directives and the namespaces where the tag prefixes reside. This element corresponds to the @ Register directive on an ASP.NET page. The @ Register directive lets you specify the tag prefix for a user control.
Tag prefixes associate a namespace in ASP.NET to the assemblies and namespaces that must be included for COM and user controls to work correctly. The following information is useful when configuring the controls element:
If applied to a user control, you must define the tagPrefix, tagName, and source attributes of the add child element.
If applied to a custom control, you must define the tagPrefix, namespace, and assembly attributes of the add child element. The assembly attribute is not required, if the control is in the application code directory.
You can use the same tagPrefix value to map to multiple assemblies or namespaces.
Default Configuration
The following default controls element is configured in the root Web.config file.
<pages>
<controls>
<add
tagPrefix="asp"
namespace="System.Web.UI.WebControls.WebParts"
assembly="System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
/>
</controls>
<!-- Other elements -->
</pages>