<?xml version="1.0"?>
<data><xpath expr="//field[@name='date_deadline']" position="attributes">
                  <attribute name="attrs">{'invisible': [('activity_category', '=', 'meeting')]}</attribute>
            </xpath>
            <xpath expr="//field[@name='user_id']" position="attributes">
                  <attribute name="attrs">{'invisible': [('activity_category', '=', 'meeting')]}</attribute>
            </xpath>
            <xpath expr="//button[@id='mail_activity_schedule']" position="attributes">
                  <attribute name="attrs">{'invisible': ['|', ('activity_category', 'in', ['meeting', 'phonecall']), ('id', '!=', False)]}</attribute>
            </xpath>
            <xpath expr="//button[@id='mail_activity_save']" position="attributes">
                  <attribute name="attrs">{'invisible': [('activity_category', '!=', 'phonecall'), ('id', '=', False)]}</attribute>
            </xpath>
            <xpath expr="//button[@name='action_done']" position="attributes">
                  <attribute name="attrs">{'invisible': ['|', ('activity_category', '=', 'meeting'), ('chaining_type', '=', 'trigger')]}</attribute>
            </xpath>
            <xpath expr="//field[@name='note']" position="attributes">
                  <attribute name="attrs">{'invisible': [('activity_category', '=', 'meeting')]}</attribute>
            </xpath>
            <xpath expr="//button[@name='action_close_dialog']" position="before">
                  <field name="calendar_event_id" invisible="1"/>
                  <button string="Open Calendar" attrs="{'invisible': ['|', ('activity_category', 'not in', ['meeting', 'phonecall']), ('calendar_event_id', '!=', False)]}" name="action_create_calendar_event" type="object" class="btn-primary"/>
            </xpath>
        </data>