The ol' Google game:
"item code" 7.68 million hits
"item number 33.3 million
"catalog item code" 215
"catalog item number 433,000
To be sure I understand, are you saying the code looks like "EWPT-MAH-W" and the number looks like "1234567"? You want to know which system would be more popular in setting up a new catalog? Or you want to know how to refer to it? (EWPT-MAH-W)
- A.