Can't have an array of arrays?

[Costello, Roger L.]

Hello DFDL community,

My input contains an array of fruit values, separator, array of wood values, 
separator, and an array of color values:

Apple
Banana
Orange
Watermelon
Grapes
Cantaloupe
----
Oak
Pine
Maple
----
Red
Green
Purple
Blue

I thought this DFDL schema would do the trick:

<xs:element name="input">
    <xs:complexType>
        <xs:sequence dfdl:separator="%NL;" dfdl:separatorPosition="infix">
            <xs:element name="fruit" type="xs:string" maxOccurs="unbounded" 
                      dfdl:occursCountKind="implicit" />
            <xs:sequence dfdl:hiddenGroupRef="separatorGroup" />
            <xs:element name="wood" type="xs:string" maxOccurs="unbounded" 
                      dfdl:occursCountKind="implicit" />
            <xs:sequence dfdl:hiddenGroupRef="separatorGroup" />
            <xs:element name="color" type="xs:string" maxOccurs="unbounded" 
                      dfdl:occursCountKind="implicit" />
        </xs:sequence>
    </xs:complexType>
</xs:element>

<xs:group name="separatorGroup">
    <xs:sequence>
        <xs:element name="separator" type="xs:string">
            <xs:annotation>
                <xs:appinfo source="http://www.ogf.org/dfdl/";>
                    <dfdl:assert test="{. eq '----'}" />
                </xs:appinfo>
            </xs:annotation>
        </xs:element>
    </xs:sequence>
</xs:group>

Sadly, that produces this error:

[error] Schema Definition Error: occursCountKind='implicit' with unbounded 
maxOccurs only allowed for last element of a positional sequence

What is the correct way to express an array of arrays?

/Roger