Under age Rollover to Roth IRA, how do I show that on the 1040 form

My 40 year old daughter rolled over her regular IRA to a Roth IRA last October. Her 1099-R shows the correct amount of the conversion and has an X in the "taxable amount not determined" column. From the lines 15a and 15b instructions on pg 23 of the "1040 forms and instructions" booklet, she should enter the amount in column 15b since it is taxable. That is fine, but how does she show that it is a rollover into a Roth IRA and not subject to any age-related penalty?