Now you can set up criteria as a dimension member range on hypothetical, non-existing dimension members. E.g. you could set up a criteria with an Account dimension member range from account number 8000 to account number 8999.
At the time of setting up the criteria, the account numbers '8000' and '8999' did not exist in your system, but you could anyway insert them as custom values. As you, in your accounting system, add more accounts in the range 8000 to 8999, they would automatically be picked up by this criteria range.