<?xml version="1.0" encoding="utf-8"?>
<openerp>
  <data>
    <record id="view_picking_form" model="ir.ui.view">
      <field name="name">Stock picking out Split button</field>
      <field name="model">stock.picking</field>
      <field name="inherit_id" ref="stock.view_picking_form" />
      <field name="arch" type="xml">
        <field name ="state" position="before">
          <button name="split_process"
                  states="draft,confirmed,assigned"
                  string="Split"
                  groups="stock.group_stock_user"
                  type="object"
                  attrs="{'invisible': ['|', ('picking_type_code', '!=', 'outgoing')]}"/>
        </field>
      </field>
    </record>
  </data>
</openerp>

<?xml version="1.0" encoding="utf-8"?>
<openerp>
  <data>
    <record id="view_picking_form" model="ir.ui.view">
      <field name="name">Stock picking out Split button</field>
      <field name="model">stock.picking</field>
      <field name="inherit_id" ref="stock.view_picking_form" />
      <field name="arch" type="xml">
        <field name ="state" position="before">
          <button name="split_process"
                  states="draft,confirmed,assigned,partially_available"
                  string="Split"
                  groups="stock.group_stock_user"
                  type="object"
                  attrs="{'invisible': ['|', ('picking_type_code', '!=', 'outgoing')]}"/>
        </field>
      </field>
    </record>
  </data>
</openerp>

Allow to split a partially available picking
Allow to split a partially available picking
