without arguments split table with c1 c2 c3 c4.... in data block tables with c1 c2, c1 c3, c1 c4, ... columns
splits data table in <number> tables. If provided <var name> is used in "DATA <var name>=...", otherwise "dum" is used.
uses condition to find the line where to split the table. If provided <var name> is used in "DATA <var name>=..." , otherwise "dum" is used.
ex: split c1=10,20,30,40 splits the table when column c1 has values 10, 20, and 30