As described in 18.3.4, the default value of a struct consists of the value that results from setting all value type fields to their default value and all reference type fields to null. For this reason, a struct does not permit instance field declarations to include variable initializers. [Example: As such, the following example results in one or more compile-time errors:

struct Point { public int x = 1; // Error, initializer not permitted public int y = 1; // Error, initializer not permitted }

end example]

This restriction applies only to instance fields. Static fields of a struct are permitted to include variable initializers.