l10n_it_ddt/security/security.xml
<?xml version="1.0" encoding="utf-8"?>
<openerp>
<data noupdate="1">
<record model="ir.rule" id="stock_ddt_type_comp_rule">
<field name="name">Stock DDT Type multi-company</field>
<field name="model_id" ref="model_stock_ddt_type"/>
<field name="domain_force">['|',('company_id','=',False),('company_id','child_of',[user.company_id.id])]</field>
</record>
</data>
</openerp>