<?xml version="1.0"?>
<data><xpath expr="//field[@name='date_deadline']" position="attributes">
                  <attribute name="invisible">activity_category == 'meeting'</attribute>
            </xpath>
            <xpath expr="//field[@name='activity_user_id']" position="attributes">
                  <attribute name="invisible">activity_category == 'meeting'</attribute>
            </xpath>
            <xpath expr="//button[@name='action_schedule_activities']" position="attributes">
                  <attribute name="invisible">has_error or activity_category == 'meeting' or id</attribute>
            </xpath>
            <xpath expr="//field[@name='note']" position="attributes">
                <attribute name="invisible">activity_category == 'meeting'</attribute>
            </xpath>
            <xpath expr="//button[@name='action_schedule_activities']" position="before">
                  <button string="Open Calendar" invisible="activity_category not in ('meeting', 'phonecall')" name="action_create_calendar_event" type="object" class="btn-primary"/>
            </xpath>
        </data>