You can add comments to the list itself. The only requirement is that there is a space after the IP. Here's the documentation talking about syntax requirements for EDL: https://www.paloaltonetworks.com/documentation/71/pan-os/pan-os/policy/formatting-guidelines-for-an-external-dynamic-list The most relevant bit is: The external dynamic list can include individual IP addresses, subnet addresses (address/mask), or range of IP addresses. In addition, the block list can include comments and special characters such as * , : , ; , #, or /. The syntax for each line in the list is [IP address, IP/Mask, or IP start range-IP end range] [space] [comment] That said, as @BPry eluded to the comment won't show up on the firewall. The comment only exists in the list source, but if it's something you control anyway you can add the comment there.
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