Use a long text variable and fill the rows with "CopyText" commands. Example:
// Fill rows Set V[wa] "This is line 1" CopyText fromString="wa" toText="tab" -appendline
Set V[wa] "This is line 2" CopyText fromString="wa" toText="tab" -appendline
Set V[wa] "This is line 3" CopyText fromString="wa" toText="tab" -appendline
...
Call .... ... table.ITAB_LINES="tab"
For structured table lines use symbolic notation. Example:
Set V[wa] "" Set V[wa](KNA1-KUNNR) "&V[mykunnr]" Set V[wa](KNA1-NAME1) "&V[myname1]"
CopyText fromString="wa" toText="tab" -appendline