For example, adding this attribute to parameter 'T on a type definition C<'T> means that a type C only supports equality if the type X also supports equality and all other conditions for C to support equality are also met. The type C<'T> can still be used with other type arguments, but a type such as C<(int -> int)> will not support equality because the type (int -> int) is an F# function type and does not support equality. This attribute will be ignored if it is used on the generic parameters of functions or methods.