The xs:anyAttribute element indicates that the resulting XML document can contain any attributes.
There are further restrictions that can be placed on the attributes that can appear in the XML document (See properties).
In essence this is a wild card, allowing any element to contain any undefined attributes.

An <anyAttribute> can be added to an element or complexType. This can be done using the right click context menu on any of these entities.

Id	A user defined ID to uniquely identify the entity within the schema
Namespace	Allows you to specify that the undefined attributes must belong to the a given namespace. This may be a list of namespace's (space separated). There are also 3 built in values ##any, ##other, ##targetnamespace, ##local. Consult the XSD standard for more information on this.
Process Contents	Options are Lax - if there is a schema to validate the attribute, then it must be valid against it, if there is no schema, then that's OK Strict  - There must be a definition for the attribute available to the parser, and it must be valid against it Skip  - no validation is performed - but it must be well formed XML

The following XSD code

<xs:element name="AdditionalInfo">

<xs:complexType>

<xs:anyAttribute />

</xs:complexType>

</xs:element>

Will be represented like this

Sample XML would look like this

<AdditionalInfo Height="174" Weight="76" />

Properties that apply to a type are shown inline at the bottom of the items container.

Values that are inherited from the base types are shown in brackets, values specifically set against the item are shown without brackets.

If a facet is not valid for a given type (typically because of its data type), then its value is shown in red.