Is there any code that states that A brand of breaker can or cannot be used in B brand of panel?

As many are aware...ITE, Cutler-Hammer, Siemens, and Westinghouse breakers are all interchangeable.

Ontario Electrical Safety Code - 2002'

2-034 Use of Approved Equipment (see Appendix B) No one shall use any electrical equipment other than approved electrical equipment of a kind or type and rating approved for the specific purpose for which it is to be employed.

2-026
2-034
As a condition of approval of certain types of electrical equipment, the manufacturer supplies instructions pertaining to its installation. It is of the utmost importance that the installer closely follow installation instructions supplied by the manufacturer to fulfill the terms of the approval agreement.

Tony Moscioni
Electrical Inspector
Electgrical Safety Authority