As shown in the ILAsm signatures, many of the types in the standard library have the predefined attribute serializable attached. A type that is marked with this attribute is to be serialized as part of the persistent state of a value of the type. This standard does not require that a conforming implementation provide support for serialization (or its counterpart, deserialization), nor does it specify the mechanism by which these operations might be accomplished.
Consider the ILAsm and C# signatures in the XML for System.String:
[ILAsm]
.class public sealed serializable String …
[C#]
public sealed class String …
Although the C# standard does not address the issue of serialization, if this library type is written in C#, when the C# declaration above is compiled, the intent is that the code generated for the class contains the serializable attribute as shown. [Note: Some implementations provide an attribute type, System.SerializableAttribute, for this purpose. end note]