A filter for the reference manual help file could be handy. I don't see it as an option and I assume there isn't one right now.

The .NET 2.0 ref manual is created with DocumentX 5. It doesn't allow me (or I can't find it) to specify a filter keyword so you can use it in filters in vs.net. However it was the only way to create a refmanual for .NET 2.0.

Though as I personally hate the VS.NET helpfile format, I also created a .chm version, which is in general more usable, because the help file is opened instantly, while vs.net takes ages to open help.