ASP.NET 3.5 ClientIDs refined

Question

I've created a simple ASP.NET 4.0 application to see how rendered client ids will vary if I change controlRenderingCompatibilityVersion in web.config and ClientIDMode attribute of the control. Now I've set <pages controlRenderingCompatibilityVersion="3.5"/> and <asp:Label runat="server" ID="Message" ClientIDMode="AutoID" /> and expect to find in the generated markup asp.net-3.5-style ClientID (something like id='ctl00_Message'), but I see this <span id="Message">Hello world!</span>.

Why does not ASP.NET render it as a 3.5-style id?

Answer 1

If the span is on it's own, then there is no reason to change the ID.

It depends if the control is inside another control. If the span above is inside a Repeater, DataList etc, then the Id will change.