directives in ASP.NET : Directory Structure « ASP.Net Instroduction « ASP.NET Tutorial

Directive           Description
Assembly            Links an assembly to the Page or user control for which it is associated.
Control             For using with user controls (.ascx). 
Implements          Implements a specified .NET Framework interface.
Import              Imports namespaces into the Page or user control.
Master              Set master page. It be used only with master pages (.master). 
MasterType          Associates a class name to a Page in order to get at strongly typed references.
OutputCache         Controls the output caching policies of a Page or user control.
Page                Enables you to specify page specific attributes and values to use when the page parses or compiles. 
PreviousPageType    Enables an ASP.NET page to work with a postback from another page in the application.
Reference           Links a Page or user control to the current Page or user control.
Register            Associates aliases with namespaces and class names for notation in custom server control syntax.

1.2.Directory Structure
1.2.1.Application Directory Structure
1.2.2.ASP.NET Application Folders
1.2.3.ASP.NET Page Directives
1.2.4.directives in ASP.NET
1.2.5.@Page directive
1.2.6.Page Directives, code section and layout