Thank you for joining the community. The Box 20 code is AH for 'other information.' Many preparers will describe the other information in supplemental pages. I think your PTP is telling you they have 8 separate 'other information' items and they call them AH1 to AH8. In ProSeries, you would enter 8 separate entries in Box 20,  with the code AH and the amount each time. Then review the supplemental information to determine what the 'other information' is. You may need to include some or all of those amounts on other schedules, based on what it is. 

Good luck!