Note  that the first column (titled “one”) is not present in the “Choose column” button (which is only displayed if in “responsive” mode); that is, it is considered “essential” to the display of this table. This technique for displaying columns does not require that any column be marked “essential.” The condition is demonstrated here only as an example of what might be done. Any column identified as “essential” will in turn cause that column’s name to be  eliminated from the selection menu (thus not permitting it to be toggled off). Note also that in responsive mode the initial display of the table will be optimized such that only the number of columns that can be displayed in the page’s width will be displayed; only columns marked “non-essential’ will be dropped during the initial display of the table, and then only of needed.