The config.php file includes the following code:

<?php 
$data['gateway']['name'] = "check";
$data['gateway']['displayname'] = "Email Only";
$data['gateway']['showas'] = "Check or Money Order";
$data['gateway']['version'] = "v1";
$data['gateway']['extraTxt'] = "Leave Blank";
$data['gateway']['extra2Txt'] = "Leave Blank";
$data['gateway']['cconsite'] = 'N';
?>

$data['gateway']['name']

(string) An internal name and it must not include any spaces.

$data['gateway']['displayname']

(string) What will be displayed to the administrator

$data['gateway']['showas']

(string) What you would like it to showas. Normally this will be Credit Card or something similar. The administrator can always change this.

$data['gateway']['version']

(string) Your version number. It is used primarily if you are going to release it for others.

$data['gateway']['extraTxt']

(string) An extra parameter. For example some gateways require the merchant id which could be entered here.

$data['gateway']['extra2Txt']

(string) An additional extra parameter. It is included in case your gateway requires two forms of authentication.

$data['gateway']['cconsite']

(string) This variable is either Y or N. Y means you are going to take the credit card on site and the site must have an SSL certificate installed. N means the gateway will handle this.