Irule to limit access to VIP to only certain source ip addresses

Hello, can someone please paste a sample content of address datagroup file? in my case, I don't to "create" datagroup file, I can only import, which is fine, so I create txt file and have the following in it: ( those are just sample IPs): 172.14.20.10/24, 172.14.21.10/24,

however it does not like it..thank you