XML schema element declarations can have simple or complex types. Elements with no element content and no attributes are declared with a simple type in the XML schema. Attribute declarations can have simple types. In general, elements with simple types and attributes are mapped to fields in  LiveCycle Designer ES. The type of the field is determined from the simple type value.
An XML schema element or attribute declaration of any base type that declares one or more enumerated values will generate a drop-down list object rather than the default field for the declaration’s base type, as shown by the following example:
<xsd:complexType>
<xsd:simpleContent>
<xsd:extension base=”xsd:string”>
<xsd:enumeration value=”red”/>
<xsd:enumeration value=”green”/>
<xsd:enumeration value=”blue”/>
</xsd:extension>
</xsd:simpleContent>
</xsd:complexType>
Whenever possible, the restriction facets that control bounds (minInclusive, minExclusive, maxInclusive, and maxExclusive), length (length, minLength, and maxLength), and precision (totalDigits and fractionDigits) are mapped to properties on generated objects. Otherwise, they are used to generate validation scripts. Here are two examples:
List types allow definition of types whose values are whitespace-separated lists of single values. Elements and attributes that have list types will be mapped to Text Field objects.
Union types are types for which the set of allowed values are a union of two or more other sets of values. The various sets are not necessarily of the same base type. In general, union types will be mapped to Text Field objects. However, in the case where all the sets in the union are of the same type, the mapping will be the same as for any type by using one of those sets (that is, a union of two sets of enumerated values will generate a drop-down list with all values from the union).

Simple types