The file extension ASCX identifies ASP.Net user controls. It is reusable code that can be accessed in ASP.Net web pages. Ascx files are simple text files that can contain ASP.Net code as well as functions in .Net languages like C # and Visual Basic.
Alternatively, a C # or Visual Basic file is referenced in an ASCX file, which provides the functionalities, while the ASCX file contains only the ASP.Net code for the web page elements. The referenced files usually have a double ending like ascx.Cs or ascx.Vb.
By default, the .Net framework also provides ASCX files, such as a user login or an input field, which can be used with Visual Studio, for example.
Please note that for newer versions of Adobe Dreamweaver the extension 'ASPNet_Support.Mxp' found in the Dreamweaver program folder under 'configurationDisabledFeatures' has to be installed first.