Just like when working with Web part pages, you can attach a different master page to that of the current site master page to an ASPX page that you’ve created in SharePoint Designer.
This section explains how you can attach a different master page to an existing ASPX page that has been created without a master page.
When you create a new ASPX page in SharePoint Designer that page does not include any Web part zones. As a result, you see the dialog shown in Figure 13.29 when you open a new ASPX page.
When creating new ASPX pages ...