[WebMethod] and EnableSession

I have a pagemethod defined with the attribute [WebMethod]. The pagemethod accesses the session with no problem (HttpContext.Current.Session).
However I just read somewhere that in order to access the session in a WebMethod, you need to define it like so: [WebMethod(EnableSession=true)]
So my question is, what gives? How come I can access the session even though I dont have that code? Apparently EnableSession defaults to false if its missing, so I should not be able to access the session.
The web application uses ASP.NET 3.5 and uses InProc Cookieless sessions.




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