Example should be "17.1.2" or some valid tags and a note should be present stating how to get those values ... IE: know your release versions.

• EL8_TAGS: The tags of the UBI8 images, for example, EL8_TAGS='"tag":"rhel_8_rhosp17.1",'.
• EL9_TAGS: The tags of the UBI9 images, for example, EL9_TAGS='"tag":"rhel_9_rhosp17.1",'.

https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/17.1/html-single/framework_for_upgrades_16.2_to_17.1/index#performing-the-overcloud-adoption_overcloud-adoption