To add rows, send an Add Rows message and specify how many rows. You can also specify after which row to insert the new rows. The arguments can either be numbers or expressions that evaluate to numbers.
dt << Add Rows( 3 ); // add 3 rows to bottom of data table
dt << Add Rows( 3, 10 ); /* add 3 rows after the 10th row, moving the 11th and lower rows farther down */
A variation of Add Rows lets you specify an argument yielding a list of assignments. Assignments can be separated with commas or semicolons.
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
dt << Add Rows(
	{:name = "Peter", :age = 14, :sex = "M", :height = 61, :weight = 124}
);
add point = Expr(
	dt << Add Rows( {:xx = x ; :yy = y} )
);
dt = New Table( "Cities" );
dt << New Column( "xx", Numeric );
dt << New Column( "cc", Character, width( 12 ) );
 
dt << Add Rows( {xx = 12, cc = "Chicago"} ); // single list
dt << Add Rows( {xx = 13, cc = "New York"}, {xx = 14, cc = "Newark"} );
// several lists
dt << Add Rows(
	{{xx = 15, cc = "San Francisco"}, {xx = Sqrt( 256 ), cc = "Oakland"}}
); // list of lists
 
a = {xx = 20, cc = "Miami"};
dt << Add Rows( a ); // evaluate as single list
 
b={{xx = 17, cc = "San Antonio"},{xx = 18, cc = "Houston"}, {xx = 19, cc = "Dallas"}};
dt << Add Rows( b ); // evaluate as list of lists

Help created on 9/19/2017