Base class for describing an XML attribute.
| defaultValueAsString | The default value for the attribute, as a string. |
| name | The attribute name. |
| obsoleteNames | A list of obsolete names for this attribute. |
| restriction | Restrictions on the possible values of the attribute. |
| type | Attribute type. |
| typeNamespace | Attribute namespace. |
| use | Whether the attribute is optional, required or prohibited. |
| GetValueFromBag | Get the attribute value from the attribute bag. |
| TryGetValueFromBag | Tries to get the attribute value from the attribute bag. |