DIM i
 
 WHILE DATA$[i] <> "EndOfData"
   PRINT DATA$[i]
   INCR i
 WEND
 
 DATA "111", "222", "333", "444"
 DATA "555", "666", "777", "888"
 DATA "999", "EndOfData"

Result:

 111
 222
 333
 444
 555
 666
 777
 888
 999