<record id="acquisition" is-extension="true" type="record,procedure">

    <!-- Information about your extension schema goes here -->
    <services-record-path id="mmi">acquisitions_mmi:http://collectionspace.org/services/acquisition/local/mmi,acquisitions_mmi</services-record-path>
    <section id="acquisitionInformation">
        <field id="acquisitionMethod">
            <options>
                <option id="gift" default="yes">Gift</option>
                <option id="purchase">Purchase</option>
                <option id="bequest">Bequest</option>
                <option id="loan">Loan</option>
                <option id="restricted-gift">Restricted Gift</option>
            </options>
        </field>

        <field id="extent" section="mmi" datatype="text"></field>
    </section>
</record>

<record id="acquisition" is-extension="true" type="record,procedure">

    <!-- Information about your extension schema goes here -->
    <services-record-path id="mmi">acquisitions_mmi:http://collectionspace.org/services/acquisition/local/mmi,acquisitions_mmi</services-record-path>
    <section id="acquisitionInformation">
        <field id="accessionDateGroup" datatype="date" ui-type="date">
            <selector>acquisition-accessionDateGroup</selector>
            <container-selector>acquisition-accessionDateGroup-container</container-selector>
        </field>
        <field id="acquisitionMethod">
            <options>
                <option id="gift" default="yes">Gift</option>
                <option id="purchase">Purchase</option>
                <option id="bequest">Bequest</option>
                <option id="loan">Loan</option>
                <option id="restricted-gift">Restricted Gift</option>
            </options>
        </field>

        <field id="extent" section="mmi" datatype="text"></field>
    </section>
</record>

Set accessionDateGroup field as calendar date
Set accessionDateGroup field as calendar date
