side (Sides)

b2boptic → items → item → pair → lens

values	description
RIGHT	lens for right eye
LEFT	lens for left eye
UNDEFINED	only allowed if a single lens is ordered and it is unknown if the lens is for right or left eye

<xs:simpleType name="Sides">
  <xs:restriction base="xs:string">
    <xs:enumeration value="RIGHT" />
    <xs:enumeration value="LEFT" />
    <xs:enumeration value="UNDEFINED" />
  </xs:restriction>
</xs:simpleType>