What's the simplest CIM form possible/recommended?

[golevel]

We're making an app that will be using the CIM method for billing our clients monthly. In our billing area where the user must fill out the form for their credit card information, we'd like to make it as simple as possible. There are a LOT of fields in the CIM documentation, many of which are listed as optional.

My questions are:

1. What is the simplest possible list of fields that we must collect? Just creditcard and expiration date?

2. Does collecting additional fields actually *do* anything? If yes, what fields and what do they do?

The documentation is really cut and dry and we'd like to actually understand how the information will be used and why we should or should not collect certain information.

[TJPride]

As usual, my advice is to largely ignore the documentation and look at the CIM.markdown file in the doc folder of your SDK. For instance:

To create a new cusomter profile, first create a new AuthorizeNetCustomer
object.

$customerProfile = new AuthorizeNetCustomer;
$customerProfile->description = "Description of customer";
$customerProfile->merchantCustomerId = 123;
$customerProfile->email = "user@domain.com";

You can then create an add payment profiles and addresses to this
customer object.

// Add payment profile.
$paymentProfile = new AuthorizeNetPaymentProfile;
$paymentProfile->customerType = "individual";
$paymentProfile->payment->creditCard->cardNumber = "4111111111111111";
$paymentProfile->payment->creditCard->expirationDate = "2015-10";
$customerProfile->paymentProfiles[] = $paymentProfile;

Just experiment a bit and then use the documentation as reference on specific fields.

[golevel]

I should have been more specific. I'm not looking for code answers, I'm more looking for theory here:

What's the point of collecting some of the "optional" fields like CCV code, address, zipcode, etc when the only required fields are cc number and expiration? I've read that CCV code is necessaryish for Visa cards, but what other "necessities" exist that are listed as optional?

[TJPride]

I think CCV isn't required, but you get lower charges from the credit card companies if you include it. Generally a good idea anyway from a security standpoint. As for the other fields - you can verify that the address matches the billing address on the card, which is another useful security feature, and of course when you look at your transactions in the Authorize.net account area it's useful to be able to see which charge was applied to who. I think that info is also included in the automatic emails people get when they're billed, unless you turn that off and send your own emails.