I think you have an oversight in the documentation for the new WCF options. All three options have the same description, makes sense for the first one...
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EmitDefaultValue
Gets or sets a value that specifies whether to serialize the default value for a field or property being serialized.
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IsRequired
Gets or sets a value that specifies whether to serialize the default value for a field or property being serialized.
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Order
Gets or sets a value that specifies whether to serialize the default value for a field or property being serialized.