data group list export error- invalid format.

I have a list of 100 IPs that I want to use in an irule. I have created a data group list and was trying to export it but keep getting the error message that "the data group external file has an invalid format, line 1"

so I have tried different formats:

network 10.0.0.0 mask 255.255.255.255,

network 20.0.0.0 mask 255.255.255.255, and so on....

and I have tried host 10.0.0.0, host 20.0.0.0

I have tried both with and without commas but nothing is working. what is the correct format?

any help would be appreciated.