This does work for me
Names Default To Here(1);
// Open a data table or replace "Data Table Name" with the name of your data table
dt = Current Data Table();
// Get the all column names from the data table
columnNames = dt << Get Column Names("String");
// Choose the specific column
cl = New Window("Column Selection",
	<<Modal,
	H List Box(
		Panel Box("Make a selection",
			V List Box(allcolumn = Radio Box(columnNames, prmtr = allcolumn << get))
		)
	)
);
//Text Box Put value spec limit Upper & Lower
wd = New Window("Spec Limit",
	<<modal(),
	H List Box(Text Box("HighL:"), High_Limit = Number Edit Box("", <<set width(10)), ),
	Button Box("OK", HighL = High_Limit << get)
);
	
// If cancel or X was clicked, stop the script
If(wd == {Button(-1)}, Stop());	
		
wd = New Window("Spec Limit",
	<<modal(),
	H List Box(Text Box("LowL:"), Low_Limit = Number Edit Box("", <<set width(10)), ),
	Button Box("OK", LowL = Low_Limit << get)
);
// If cancel or X was clicked, stop the script
If(wd == {Button(-1)}, Stop());
//Put value Spec Limit on choosen column
col = Column(prmtr);
Eval(EvalExpr(
	col << Add Column Properties(
		Set Property(
			"Spec Limits",
			{LSL(Expr(LowL)), USL(Expr(HighL)), Show Limits(2)}
			
		)
	)
));
Also if you would like to, you could combine all those selections into a single modal window
Names Default To Here(1);
dt = Current Data Table();
col_names = dt << Get Column Names("String", Continuous);
nw = New Window("Set Specs", << Modal,
	H List Box(
		Panel Box("Select Column",
			rb_col = Radio Box(col_names)
		),
		Panel Box("Select Limits",
			Lineup Box(N Col(2),
				Text Box("LSL: "),
				lsl_neb = Number Edit Box("", <<set width(10)),
				Text Box("USL: "),
				usl_neb = Number Edit Box("", <<set width(10))
			)
		),
		Panel Box("Actions",
			Lineup Box(N Col(1),
				Button Box("OK",
					lsl_val = lsl_neb << get;
					usl_val = usl_neb << get;
					sel_col = rb_col << get selected;
				),
				Button Box("Cancel")
			)
		)
	)
);
If(nw["Button"] != 1,
	Throw("Cancel pressed");
);
show(sel_col, lsl_val, usl_val);
					
				
			
			
				
	-Jarmo