Add Custom Tables to Lawson Data Dictionary

I am looking to add handful of custom tables to database and then build programs to extract data using the custom tables. Would like to know the process which helps me doing this. Thank you!!

You want the Lawson 4GL Workbooks. As far as I recall, those weren't available online, as they are considered part of Training/Infor Learning, but if you search for dbdef and pgmdef, it will point you in the right direction