Cell-Rows-Span
This property allows you to group several cells on the y-axes in the column heading.
The value of this property specifies how many cells should be merged together on the y-axes starting from the row identified by the Y property in the column identified by the X property.
Point the first of the merged rows to inquire or modify the content of the merged cells.
 
Example - In a grid where the first three rows are column headings, merge rows number 2 and 3 within the first column and put the title "Col.1" in the merged cells
procedure division.
...
  modify screen-1-gr-1(2, 1cell-rows-span 2
  modify screen-1-gr-1(2, 1cell-data "Col.1"
...