Sage 100 ERP v3.70 to 4.30 file layouts link - does not appear to require login. Handy for providing to customers who want the layout to help with report writing, etc. Starting with version 4.4 these are within Sage 100 under Resources - File Layouts.
https://partners.sagenorthamerica.com/irj/go/km/docs/sageKM/Sage%20MAS%2090%20and%20200/Assets/file_info/file_layout_info.htm