stock_view.xml

<?xml version="1.0" encoding="UTF-8"?>
<openerp>
	<data>
		<record id="view_picking_shipping_usps" model="ir.ui.view">
			<field name="name">stock.picking.shipping.usps</field>
			<field name="model">stock.picking.out</field>
			<field name="inherit_id" ref="shipping_api.view_picking_shipping_inherit"/>
			<field name="priority" eval="20"/>
			<field name="arch" type="xml">
				<xpath expr="//page[@string='Shipping']/notebook/page[@string='Shipment']" position="after">
				<page string="USPS">
				 	<group colspan="4" col="4" >
						<separator string="USPS" colspan="4"/>
						<field name='usps_service_type' attrs="{'required': [('ship_company_code','=','usps')]}"/>

						<field name='usps_package_location' attrs="{'required': [('ship_company_code','=','usps')]}"/>
						<field name='usps_confirmation_number' invisible="1"/>

						<field name="usps_container"/>
						<field name="usps_size"/>
                        <field name="usps_first_class_mail_type" attrs="{'required':[('usps_service_type','in',('First Class','First Class HFP Commercial'))], 'invisible':[('usps_service_type','not in',('First Class','First Class HFP Commercial'))]}"/>
                        <!-- group colspan="4" col="4" attrs="{'invisible':[('usps_size','!=','LARGE')]}" >
                            <separator string = "USPS Dimension" colspan="4" />
                            <field name="usps_width" />
                            <field name="usps_length" />
                            <field name="usps_height" />
                            <field name="usps_girth" attrs="{'invisible':['|', ('usps_container','!=','Non-Rectangular'), ('usps_container','!=','Variable'), ('usps_container','!=','')]}" />
                        </group -->
					  </group>
				</page>
				</xpath>
			</field>
		</record>

		<record id="stock_packages_form_usps" model="ir.ui.view">
            <field name="name">stock.packages.form.usps</field>
            <field name="model">stock.packages</field>
            <field name= "inherit_id" ref="shipping_api.stock_packages_form"/>
            <field name="arch" type="xml">
              	<field name="tracking_url" position="after" >
              		<field name="usps_confirmation_number" invisible="1"/>
             	</field>
            </field>
		</record>
	</data>
</openerp>