Field definitions are composed of a name and a location signature. The location signature defines the type of the field and the accessing constraints, see §I.8.6.1. A value type or object type shall define only one field of a given name and type. However, a derived object type can have fields that are of the same name and type as its base object type. See §I.8.10.1 and §I.8.10.4.
The name of the field is scoped to the type (see §I.8.5.2). Fields can be given accessibility attributes, see §I.8.5.3. Fields shall only store values whose types are assignable-to (§I.8.7.3) the type of the field (see §I.8.3.1).
Fields can be marked as static, indicating that the field is not part of values of the type but rather a location associated with the type as a whole. Locations for the static fields are created when the type is loaded and initialized when the type is initialized.
Fields not marked as static define the representation of a value of a type by defining the substructure of the value (see §I.8.4.1). Locations for such fields are created within every value of the type whenever a new value is constructed. They are initialized during construction of the new value. A non-static field of a given name is always located at the same place within every value of the type.
A field that is marked serializable 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), not does it specify the mechanism by which these operations might be accomplished.