Configuration/Core/client/html/common/address/billing/mandatory

Summary
List of billing address input fields that are required

client/html/common/address/billing/mandatory = Array (   [0] => order.base.address.salutation    [1] => order.base.address.firstname    [2] => order.base.address.lastname    [3] => order.base.address.address1    [4] => order.base.address.postal    [5] => order.base.address.city    [6] => order.base.address.languageid    [7] => order.base.address.email )


 * Default: Array
 * Type: array - List of field keys
 * Since: 2014.03

Description
You can configure the list of billing address fields that are necessary and must be filled by the customer before he can continue the checkout process. Available field keys are:
 * order.base.address.company
 * order.base.address.salutation
 * order.base.address.firstname
 * order.base.address.lastname
 * order.base.address.address1
 * order.base.address.address2
 * order.base.address.address3
 * order.base.address.postal
 * order.base.address.city
 * order.base.address.state
 * order.base.address.languageid
 * order.base.address.countryid
 * order.base.address.telephone
 * order.base.address.telefax
 * order.base.address.email
 * order.base.address.website