Am studying for the CPC exam and need clarification on the following:

If an + (Add-on sign) follows a main entry, does this mean the listed Add-on code covers, for instance, more than one digit, etc. in the same operation/service by the (same) physician.

The CPT states, and I understand, too, the + is exempt from modifer 51 (multiples), but I am finding this a quagmire. In an AAPC article on Add-ons, people are arguing that modifiers can be used. I don't read the CPT Guideline that way, so I figure I am missing something important somewhere.

For instance, and this is only my own example, if I code 26125 (the Add-On), is this the only code that would be used in conjunction with code 26123? Or, would I take the main code 26100 (Arthrotomy with biopsy, carpometacarpal joint, each), then list code 26123 (Fasciectomy . . . .), then the Add-On?

What is confusing to me is, if this was a physician removing a finger, for instance, and finds he has to remove one or more "digits" as a connective problem, would he still use only one Add-on code (same operation, same problem)? So, too, what does "list separately" mean?

Would appreciate input here. Make it simple, please?