What is the maximum length of request parameters?

The maximum length of all request parameters is 100 characters, except the following: 200 characters for custom_fields, 500 characters for card_hash, 64 characters for the session_id (sent directly or within the session field), 19 characters for the phone_number, 15 characters for card_bin, 4 characters for transaction_currency, 50 characters for discount_code and shipping_method and 255 characters for transaction_id.