In a DTD, can an attribute be in only one of two declared elements?

Question

I have to write a DTD valid for this XML document:

<orders>    
    <order>
        <_id ord_date="2020-03-01" status="A">1.0</_id>
        <cust_id>Ant O. Knee</cust_id>
        <items>
            <element>
                <price>2.5</price>
                <qty>5.0</qty>
                <sku>oranges</sku>
            </element>
            <element>
                <price>2.5</price>
                <qty>5.0</qty>
                <sku>apples</sku>
            </element>
        </items>
        <price>25.0</price>
    </order>
    <order>
        <_id>3.0</_id>
        <cust_id ord_date="2020-03-08" status="A">Busby Bee</cust_id>
        <items>
            <element>
                <price>2.5</price>
                <qty>10.0</qty>
                <sku>oranges</sku>
            </element>
            <element>
                <price>2.5</price>
                <qty>10.0</qty>
                <sku>pears</sku>
            </element>
            <element>
                <price>0.0</price>
                <qty>1.0</qty>
                <sku>gift</sku>
            </element>
            <element>
                <price>0.0</price>
                <qty>1.0</qty>
                <sku>gift</sku>
            </element>
        </items>
        <price>50.0</price>
    </order>
</orders>

As you can see, I have to declare the attribute ord_date and status inside _id or cust_id but it has to be in only one of those two.

I have tried to declare it like this, but this DTD allows to be in both, in one of them or in none of them.

<!ELEMENT orders(order)+>
<!ELEMENT order(_id, cust_id, items, price)>
<!ELEMENT _id>
<!ELEMENT cust_id (#PCDATA)>
<!ELEMENT items (element)+>
<!ELEMENT element (price, qty, sku)>
<!ELEMENT price>
<!ELEMENT qty>
<!ELEMENT sku (#PCDATA)>
<!ATTLIST _id ord_date CDATA #IMPLIED>
<!ATTLIST cust_id ord_date CDATA #IMPLIED>

How can I declare this DTD correctly?