svg:BaselineShiftValueType 

The actual definition is
baseline | sub | super | <percentage> | <length> | inherit 
not sure that union can do this

Simple Type Information

Used By

Attribute svg:PresentationAttributes-TextContentElements/@baseline-shift

Source 

<simpleType name="BaselineShiftValueType">
  <annotation>
    <documentation>The actual definition is baseline | sub | super | <percentage> | <length> | inherit not sure that union can do this</documentation>
  </annotation>
  <restriction base="string"/>
</simpleType>