Label lines provide column headings in tabular displays. You can change the column headings used to describe different sections of a tabular display by embedding label lines in the existing multiple-line WTO message for a tabular display.
Authorized programs (supervisor state, or PSW key 0-7, or APF-authorized) that are authorized to add lines to an existing multiple-line WTO message are also permitted to embed label lines within that existing multiple-line WTO message. The label line does not have to appear immediately following the control line and before the data lines. At most two label lines can appear consecutively without an intervening data line.