Commerce & PayPal - What does "Solution Type" mean? Our site is using the Craft Commerce plugin, and within that we've enabled the PayPal Express gateway. However, there is a very cryptic dropdown menu on the gateway settings page...



So my question is, what is the "Solution Type"?

What does that even mean? And what is the difference between the "Sole" and "Mark" options?
Ignore the terminology, it really makes no sense. What it should say is this...

Require customers to use a PayPal account?


[Sole] No, a PayPal account is optional. Customers can still choose to pay with a credit card instead.
[Mark] Yes, a PayPal account will be required to complete a purchase.




Here's a screenshot of the documentation...



So why did PayPal decide to call this particular choice "Solution Type"?

And what do "Sole" and "Mark" actually mean?

The world may never know.