Hi!
From my SCDJWS study notes:
Complex types can be declared containing the <all> element in the place of the <sequence> element. The <all> element cause the elements of the complex type to:
• Child elements of the complex type can appear in any order.
• Child elements always have a maxOccurs of 1 and a minOccurs of 0.
• Only single elements may occur in an <all> group.
No groupings like <sequence> or <all> can occur in an <all> group, however, custom types declared using either <simpleType> or <complexType> can occur in an <all> group.
I don't see why you want to include the minOccurs attribute on the <all> element - see above about minOccurs and maxOccurs of the child elements of the <all> element.
If you want the <partsValue> element to be optional, this is what you'd write in your schema:
If you use <all>, you cannot choose whether a child element of <all> is to be optional or not - they all are optional and can, at most, occur once.
Best wishes!