Why is dfdl:lengthUnits=bytes required with lengthKind=prefixed?

[Costello, Roger L.]

Hi Folks,

My input is this:

8John Doe

I used lengthKind=prefixed in my schema. See below. Notice on the element 
declaration for "name" I specify dfdl:lengthUnits="bytes". I originally 
specified "characters" instead of "bytes" and that resulted in an error 
(unconsumed data). This is so counterintuitive. First, why do I even need to 
specify lengthUnits on "name"? Second, although I don't' show it, I tried 
putting lengthUnits on the simpleType and it didn't matter what value I 
assigned to lengthUnits ... I thought you always had to specify lengthUnits 
whenever you specify lengthKind=explicit ... apparently not. I couldn't find 
any explanation of this in the specification.  /Roger 

<xs:element name="input">
    <xs:complexType>
        <xs:sequence>
            <xs:element name="name" 
                type="xs:string" 
                dfdl:lengthKind="prefixed" 
                dfdl:lengthUnits="bytes" 
                        dfdl:prefixLengthType="prefix-type"  
                dfdl:prefixIncludesPrefixLength="no"/>
        </xs:sequence>
    </xs:complexType>
</xs:element>

<xs:simpleType  name="prefix-type" 
                dfdl:lengthKind="explicit"
                dfdl:length="1">
    <xs:restriction base="xs:integer" />
</xs:simpleType>