We can classify xs:simpleTypes into 4 categories

Base types defined in the W3C XSD standard

These are the built in types, and map directly to the native language types.

xs:list types

Types created using the xs:list construct are generated as arrays of items.

<xs:element name="ListOfStrings"
            xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:simpleType>
        <xs:list itemType="xs:string" />
    </xs:simpleType>
</xs:element>

public string[] ListOfStrings {get;set;}

A union of several different xs:simpleTypes

If a type is formed using the xs:union notation from several different simple types then a class is generated from it (see handling xs:union)

Restrictions of an existing xs:simpleType

If a xs:restriction is applied to an existing type (in our example we are RestrictedString restricts xs:string), then the native type that represents the XSD type being restricted (xs:string -> System.String) is still used as the type.  Details of the restriction are added as attributes against the property. This has no impact on the interface generated, but affects the validation performed during serialization and deserialization.

    <xs:element name="RestrictedString">
        <xs:simpleType>
            <xs:restriction base="xs:string">
                 <xs:pattern value="(\d)*" />
                <xs:length value="5" />
            </xs:restriction>
        </xs:simpleType>
    </xs:element>

[LxElementValue("RestrictedString", "", LxValueType.Value, XsdType.XsdString, Length="5", Pattern="(\\d)*"]
public System.String RestrictedString{ get; set; } = "";