account_payment_term_extension/account_demo.xml

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

<openerp>
<data noupdate="1">

<record id="account.account_payment_term_line" model="account.payment.term.line">
    <field name="days" eval="0"/>
    <field name="months" eval="1"/>
</record>

<record id="sixty_days_end_of_month" model="account.payment.term">
    <field name="name">60 Days End of Month</field>
    <field name="note">60 Days End of Month</field>
</record>

<record id="sixty_days_end_of_month_line" model="account.payment.term.line">
    <field name="payment_id" ref="sixty_days_end_of_month"/>
    <field name="value">balance</field>
    <field name="months" eval="2"/>
    <field name="days" eval="0"/>
    <field name="days2" eval="-1"/>
</record>

</data>
</openerp>