IllustratorSaveOptions - Compatibility Javascript reference for CC2019

Hi all,

I'm trying to write into a Javascript to save back from the latest Ai2020 version 24.1.3 to CC2019.

I can't seem to find an updated reference that works for "Compatibility.ILLUSTRATOR19"

There is a suggestion here: scripting-constants-compatibility but just upping the version number from an existing script which I use to save back to Ai8 doesn't work. I receive the following error:

I've tried swapping "19" for "CC", as per the display in the save as dialog panel but to no avail.

Code snippet is here:

// Save with AI2019 compatibility
// AI2019 save options  
var so = new IllustratorSaveOptions();
so.compatibility = Compatibility.ILLUSTRATOR19; 
so.pdfCompatible = true; 
so.embedLinkedFiles = false; 
so.embedICCProfile = true; 
 

// save as 2019 overwriting 2020 version  
doc.saveAs(File(originalDocPath + "/" + originalDocName + "_legacy.ai"), so);  

app.activeDocument.close();

Does anyone have any ideas on the update reference for compatibility to 2019 please?

Thanks.