Go to Metadata - static field handling is wrong
Navigate to System.Char.
Notice that the MaxValue and MinValue fields are listed as static vals. This is wrong. They cannot just be marked with [<DefaultValue>] either.

If we follow the error message you would get if you tried to write this into your own signature, it compiles:

But this is no longer correct, since the value in question is a public const field.
This may be a current limitation in the language, actually. We don't really have a good way to declare these things in F# code today. We can probably still get things to "work" in metadata as source view though, at least getting colors and maybe navigation going.
Some context from http://www.ianvoyce.com/index.php/2010/10/01/public-static-fields-gone-from-f-2-0/:
We deliberately removed the ability to create public static fields in Beta2/RC, because of issues associated with initialization of the fields (i.e. ensuring the “static do” bindings are run correctly, and if they are run, then they are run for the whole file, in the right order, with no deadlocks or uninitialized access when initialization occurs from multiple threads).