purchase_order.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
  <data>

    <record id="purchase_order_form" model="ir.ui.view">
      <field name="name">purchase_order_form</field>
      <field name="model">purchase.order</field>
      <field name="inherit_id" ref="purchase.purchase_order_form"/>
      <field name="arch" type="xml">
        <field name="partner_id" position="after">
          <field name="is_vci" />
        </field>
      </field>
    </record>

    <record id="view_purchase_order_filter" model="ir.ui.view">
      <field name="name">view_purchase_order_filter</field>
      <field name="model">purchase.order</field>
      <field name="inherit_id" ref="purchase.view_purchase_order_filter"/>
      <field name="arch" type="xml">
        <filter name="draft" position="after">
          <filter name="is_vci" string="VCI" domain="[('is_vci', '=', True)]"/>
        </filter>
      </field>
    </record>

  </data>
</openerp>