Question on Using Partial Types with ASP.NET via J.I.T.

[nospam]

I got three (3) files

(1) Untitled.aspx
(2) Untitled.aspx.1.cs
(3) Untitled.aspx.2.cs

These three files must be used together to make file #1, Untitled.aspx, page
work via
J.I.T. when the User first hits Internet Explorer 6.0 on your browser.
MY QUESTION to the Microsoft ASP.NET and C# teams.

I know how file #2,Untitled.aspx.1.cs, is connected and can be found by file
#1, the Untitled.aspx page.
How does file #3, Untitled.aspx.2.cs, get found by the file #1 when I the
first time with Internet Explorer?

IN OTHER WORDS, I am NOT using pre-compile for VS.NET to make these file
compile together.
I would be just using J.I.T. compiling like you do now with src= attribute
in a ASP.NET page.