I've inherited a SharePoint site with some odd behavior.
In MS Office SharePoint Designer, when I "Reset to Site Definition" the "default.master" page, it still has lots of customizations, e.g. copyright year. Where does this restore come from?
I think the previous developer has modified installation files.
I've searched the drive for "default.master" and manually looked for the SharePoint installation files, but cannot find them.
You can know what is the current default master page by using this way: In MS SP Designer: In the masterpage folder, right-click the master page that you want to know, If this master page is already the default master page for the site, the "Set as Default Master Page" command is unavailable. So, this master page is the current default master page. In this way, you also can check which master page is the custom master page by using the same way as above.
One thing to remember here is that if a page shows the master page definition as "~masterurl/default.master", this does not mean that the master page is actually a file called "default.master". This is actually a tokenization used in the MasterPageFile attribute, and loads whatever value is set in the object model for SPWeb.MasterUrl or SPWeb.CustomMasterUrl depending on the page type.
This is explained in the MSDN article Customizing Master Pages in Windows SharePoint Services, where it states:
Dynamic token "~masterurl/default.master"
This token references a master page from a content page by using the MasterPageFile attribute together with the value of the MasterUrl property. As an example, in the following page directive, <%@ Page MasterPageFile="~masterurl\default.master"%>, the token "~masterurl/default.master" is replaced at run time by the value in the MasterUrl property. This property contains the server-relative full path to the master page, including file name.
At installation time, all SharePoint content pages use this dynamic token and the MasterUrl property is set to the Windows SharePoint Services default.master; however, you can change this value at any time to point to a different master page.
C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE\
In there they had modified \GLOBAL\default.master and various other .master files in \LAYOUTS\
