Get Rows returns a matrix of rows that match the specified condition. The following example select rows in which the age is greater than or equal to 16:
dt = Open( "$SAMPLE_DATA/Big Class.jmp" );
dt << Get Rows Where( :age >= 16 );
[35, 36, 37, 38, 39, 40]
Get Selected Rows returns a matrix of the currently selected rows. The following example selects rows 1, 3, 5, and 7 and then returns the row numbers in a matrix:
dt << Select Rows( {1, 3, 5, 7} );
dt << Get Selected Rows;
[1, 3, 5, 7]
Next Selected and Previous Selected scroll the data table window up or down so that the next selected row that is not already in view moves into view. The table wraps, so Next Selected jumps from the bottom-most selected row to the top-most, and vice versa for Previous Selected.
dt << Next Selected;
dt << Previous Selected;
dt << Clear Select;

Help created on 7/12/2018