The code set is always defined for the entire campaign, but sometimes you may want to use a different set for specific content within a campaign. However, you can also assign a code set to specific content (for example, in A/B tests) using a directive in a hidden form field.
in the editor, open the content and go to Form Rules.
add a new hidden field, select Process with Mailoctaorum (the so-called Opt field), name it promocode_set and enter the name of the code set as the value as you have named it
After saving the changes to the content, only codes from this set will be read for this content.
You can check the details of a successful code set change in Monitoring, where you will see a log whenever the default code set is switched to this setting.