Database.com Metadata API Developer's Guide - Salesforce.com

Metadata TypesMetadatafeedItemTypeCallLogPostfeedItemTypeTextPost...MetadataThis is the base class for all metadata types. You cannot edit this object. A component is an instance of a metadata type.Metadata is analogous to sObject, which represents all standard objects. Metadata represents all components and fields inMetadata API. Instead of identifying each component with an ID, each custom object or custom field has a unique fullName,which must be distinct from standard object names, as it must be when you create custom objects or custom fields in theDatabase.com user interface.VersionMetadata components are available in API version 10.0 and later.FieldsField NamefullNameField TypestringDescriptionRequired. The name of the component. If a field, the name mustspecify the parent object, for example Account.FirstName. The__c suffix must be appended to custom object names and customfield names when you are setting the fullName. For example, acustom field in a custom object could have a fullName ofMyCustomObject__c.MyCustomField__c.See Also:CustomObjectCustomFieldMetadataWithContentMetadataWithContentThis is the base type for all metadata types that contain content, such as documents or email templates. It extends Metadata.You cannot edit this object.VersionMetadataWithContent components are available in API version 14.0 and later.124