why is " &s2_customer_ip=" needed?

hey
its about the ccbill Buttons i like to use the html links instead of the shortcode

thats what i like to use:

https://bill.ccbill.com/jpost/signup.cgi?clientAccnum=xxxx&
clientSubacc=0000&formName=146cc&formPrice=40.00&formPeriod=365&currencyCode=840&s2_p1=0+D&s2_p3=1+Y&s2_desc=146cc&s2_invoice=1%3A%3A1+Y&s2_custom=xxxxx&s2_customer_ip=xxxxxx&s2_referencing=1&formDigest=xxxxxxx

instead of this:

[s2Member-Pro-ccBill-Button level="1" ccaps="" desc="" cc="USD" custom="xxxx" ta="0" tp="0" tt="D" ra="40" rp="1" rt="Y" rr="0" image="default" output="anchor" /]

downside is that the customer ip doesnt get automatically generated in the html link
so how is the customer ip needed? can i delete the &s2_customer_ip=xxxxxx part without any bad cause ? (link still redirect to ccbill without the customer ip)

Thank you for your inquiry.

s2Member requires this to track the sale after it’s sent back from ClickBank. You can generate a link with these buttons by changing the output attribute on the button to url. I’d recommend creating your links this way, just to keep things working with s2Member for sure. If you ever have a problem with your integration with Clickbank changing these URLs will be the first thing we’ll need to ask you to do.

using url output is great everything is alright now