First Data Payeezy Gateway Payment Page Field Validation

x_line_items	Item ID, Title, Description: Maximal length 255 Taxable: TRUE/FALSE Price, Quantity: numeric
POST date	Max length: 8000 bytes
x_version	Must be 3.0 or 3.1
x_fp_timestamp	Must be within 900 seconds of present time
x_fp_sequence	Must be empty
x_test_request	Must be empty, TRUE or FALSE
x_login	Must be configured, saved and not deleted. When configured for test mode, test terminals must be configured. The same apples for production mode.
x_show_form	Must be 'PAYMENT_FORM', cannot be empty
x_fp_hash	Must be present and calculated correctly
x_relay_response	Must be empty or TRUE
x_relay_url	Must be the same value configured in the Payeezy Gateway Payment Page settings. This is not technically a required setting for non-relay response merchants but some shopping carts do send it by default.
bypass_first_page	Must be empty, FALSE, or TRUE. If customers are offered the credit card option this value cannot be TRUE.
x_currency_code	Must be empty, or contain the relevant currency code
x_amount	Required parameter, must be a number
x_type	Must be AUTH_CAPTURE, AUTH_ONLY, AUTH_TOKEN, or PURCHASE_TOKEN
x_method	Must be empty or CC
x_recurring_billing	Must be empty or NO
x_exp_date x_card_num x_card_code x_trans_id x_auth_code x_authentication_indicator x_cardholder_authentication_value x_bank_aba_code x_bank_acct_type x_bank_name x_bank_acct_name x_echeck_type	Must be empty (features are not supported)
x_receipt_link_method	Must be empty, GET, AUTO-GET, POST, AUTO-POST, LINK, or REDI
x_email_customer	Must be empty, TRUE, or FALSE
x_tax	Must be empty or numeric
x_freight	Must be empty or numeric
x_tax_exempt	Must be empty, TRUE, or FALSE
x_duty	Must be empty or numeric

Each field may also trigger errors if they exceed the maximum length of 255 characters.

The values, x_footer_email_receipt and x_header_email_receipt may be up to 4000 characters long.