DefaultAlias returns a `Alias` struct populated with its default values.

DefaultAnnotation returns a `Annotation` struct populated with its default values.

DefaultArgument returns a `Argument` struct populated with its default values.

DefaultDirective returns a `Directive` struct populated with its default values.

DefaultDirectiveRequire returns a `DirectiveRequire` struct populated with its default values.

DefaultEnum returns a `Enum` struct populated with its default values.

DefaultEnumValue returns a `EnumValue` struct populated with its default values.

DefaultError returns a `Error` struct populated with its default values.

DefaultField returns a `Field` struct populated with its default values.

DefaultImport returns a `Import` struct populated with its default values.

DefaultImportRef returns a `ImportRef` struct populated with its default values.

DefaultInterface returns a `Interface` struct populated with its default values.

DefaultList returns a `List` struct populated with its default values.

DefaultListValue returns a `ListValue` struct populated with its default values.

DefaultLocation returns a `Location` struct populated with its default values.

DefaultMap returns a `Map` struct populated with its default values.

DefaultNamed returns a `Named` struct populated with its default values.

DefaultNamespace returns a `Namespace` struct populated with its default values.

DefaultObjectField returns a `ObjectField` struct populated with its default values.

DefaultObjectValue returns a `ObjectValue` struct populated with its default values.

DefaultOperation returns a `Operation` struct populated with its default values.

DefaultOptional returns a `Optional` struct populated with its default values.

DefaultParameter returns a `Parameter` struct populated with its default values.

DefaultParserResult returns a `ParserResult` struct populated with its default values.

DefaultReference returns a `Reference` struct populated with its default values.

DefaultStream returns a `Stream` struct populated with its default values.

DefaultType returns a `Type` struct populated with its default values.

DefaultUnion returns a `Union` struct populated with its default values.

DefaultUnionMember returns a `UnionMember` struct populated with its default values.

Alias types are used for cases when scalar types (like string) should be parsed our treated like a different data type in the generated code.

Annotations attach additional metadata to elements.

Directives are used to ensure that an annotation's arguments match an expected format.

Enumerations (or enums) are a type that is constrained to a finite set of allowed values.

Apex can integrate external definitions using the import keyword.

Interfaces are conceptual groups of operations that allow the developer to divide communication into multiple components.

Namespace encapsulates is used to identify and refer to elements contained in the Apex specification.

Types are the most basic component of an Apex specification.

Unions types denote that a type can have one of several representations.