Addin have their JSL available in one of two structures. And it turns out, the two Addins you referenced happen to cover both structures. The JSL for the Table Attributes was saved as separate files for the Addin. Because of that, you can go to the folder for the Addin and directly see the files. To find the folder and to branch to it go to
It will popup a dialog box, where you can select the Addin you want, and then the selection will provide you with the folder(directory) the Addin is stored in.
The second Addin structure, has the JSL saved directly in the Addin menu definition. To access this type of Addin, you will need to edit the .jmpaddin. To access this file for the Limits to Data Table, you will need to save the Addin file to a local disk, from the File Exchange, rather than just installing it. Once it is saved, go to
and navigate to the file you downloaded and saved. Click on the file, and then go to the down arrow next to the "Open" button and select "Open using Add-in Builder". Then click on OK. The Add-in Builder will open the Addin and within the Menu item for the Addin, you will see the embedded JSL.