What is the difference between Global Configuration TLVs and Group Configuration TLVs? Is there a priority between them?

Q: What is the difference between Global Configuration TLVs in Global 0 and other Group Configuration TLVs? Is there a priority between them?

A: The global configuration defines all the properties required for a basic transaction and the Tags applied to both CT and CTLS transactions. Each card brand transaction first refers to the linked group for that card brand to look for the TLVs it needs, then goes to the default group 0 if it does not exist in the card's specific group. For example, if a VISA transaction does not find a floor limit (Tag 9f1b) in group 0x90, the 9F1B value in group 0 will be applied to this transaction. Yes, there is a priority between group 0x90 (in this case) and group 0x00.

Q: What are the mandatory Tags that should be changed when configuring a reader for use Brazil, ?

A: There are no mandatory Tag changes, but in most cases, you will change the country code and currency code.

Q: In which configuration group should Tags be changed? In the global configuration, in a group configuration, or in all group configurations?

A: Check the AID list to find out what group each card brand is linked to, and modify the TLVs in that specific group. Note: Be very cautious when modifying the default group unless you want that Tag to be applied to ALL card brands. 

Q: What is recommended: Changing an already defined configuration group or creating a new group (a copy of the original) and changing the desired Tags?

A: For Tags that you want only apply to a specific AID, create a new group that includes all the original Tags from the already defined group with the Tags changed for this AID.

Q: How can I enable only some AIDs? For example, to allow only Visa, Mastercard, and Elo cards for debit and credit.

Use the 04-04 command to disable the unwanted system AIDs. Refer to the IDG related to the product for details.