Why support labels instead of line numbers? Line numbers are a very old concept that date back to the punched card era. Originally every line in a basic program had a line number. Using the goto of if statements was simple, you just wrote "goto lineN" or "if...then lineN" and the BASIC interpreter would locate the line and continue executing from there. Gradually things changed so that the newer more modern interpreters and compilers only needed a line number for lines that were the destination of a goto or if statement. XCSB uses labels in preference to line numbers because they can be much more informative. They help the programmer by attaching meaning to a goto statement and at the position in the program at which they appear.