Oops - I lost my data ...

[#1]

take care that you don't:

1. create a virtual link with a wrong table reference
2. create a summary table with a compact column 

[#2]

Thanks hogi,
I could rescue a few of my datasets with your solution! Highly appreciated 

[#3]

Why would you want to make your data non-accessible in such a way that it is basically corrupted?

[#4]

option 2)  create a summary table

- with a link to the main table (default)

- with a compact column

dt = New Table( "input",
	Add Rows( 3 ),
	New Column( "ID",
		Character,
		"Nominal",
		Set Values( {"A_1", "A_2", "A_3"} ),
		Compact() // <- disable to remove the bug
	)
);

dt sum = dt << Summary(	Group( :ID ),
//Link to original data table( 0 ) // <- uncomment to disable the bug
);

fn = "$temp\bug" || Char(random integer(10000))||".jmp";
dtsum  << Save( fn );
Close( dt sum, NoSave );
Try(open(fn), Caption("sorry, the file is damaged"));

When you try to open the file manually, JMP will display an error message:

bug seems to be fixed in JMP19