XML Schema Part 1: Structures (4.3.1)

Hi, all

At the end of section 4.3.1 of the XML Schema Part 1: Structures, it is
stated that, in a local or global context, "If value is present, use
must be one of default or fixed".  

Does this imply that "use" MUST be present, or does the default
behaviour apparent in the "Value Constraint" section of the preceding
schema components and properties tables apply?  


Thank you,
Elena