So, in a Suitelet I have a sublist with fields in ENTRY mode. Two such fields are checkboxes. I add a Mark All button to the sublist, and both get checked. Any way to prevent that? I only want the first one checked. That checkbox is for “Selection” of the row. The other checkbox is there to provide different custom functionality.

Not natively. You could create an INLINE HTML field that contains a script that would override what that button does, and have it only select the checkboxes with a certain ID. This would be a DOM hack, and not supported/recommended by NetSuite though

I would recommend implementing your own mark all checkbox button, the native one does not trigger all the entry points in a client script (pretty sure fieldchanged does not get fired by it, for example)

ok, thanks all - but basically not natively. thanks