A question about coins obverse classification

[justMe]

Hello,
On some coin certificates i.e. ICCS, there are notes of the type "obverse # 3" or just  "obverse 2". I have been trying to figure out what it means but no success so far.
In particular I have seen these on certificates for Canadian 10 cents dated before 1900 (queen Victoria rule).
Any suggestions?

[Figleaf]

For reliable information go here. The numbers the third party grader uses may have been plucked from a popular catalogue, perhaps Charlton.

Peter

[justMe]

Thank you for the valuable info. I actually have a Charlton 2020 guide but found no hint.
Strange that an evaluator should use a grading system that is not widely recognized.
Will keep looking
cheers Gidu