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SBASIC Manual - Page 17

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     SBasic User's Manual     SBasic Version 2.7             Page 17
     Printed:  December 5, 1999

     SBasic does not support line numbers, but it does support line labels.
     Line labels consist of a string of up to 20 characters, ending with a
     colon (:).  Labels must begin with an alphabetic character or an
     underscore ('_'); remaining characters in a label can also include
     digits.  Any text following a line label definition is ignored.

     NOTE:  Though legal, starting labels with an underscore can cause
     obscure problems if you embed assembly language in your SBasic source
     file.  See the section below on ASM and ENDASM, regarding references
     to SBasic variables from within an ASM block.

          foo:                     ' define the line label foo
               a = 3               ' write a value to A
               return              ' return from this subroutine

          main:                    ' start of the main program
               gosub foo           ' execute the subroutine foo

     This example shows several important points.  Note that labels require
     a trailing colon only when they are defined, but not when they are
     referenced.  Thus, the GOSUB to FOO doesn't need a colon at the end of

     Also, every SBasic program MUST contain the line label MAIN, even if
     it contains no other line labels.  The startup code that supports
     SBasic on the target system always jumps to the label MAIN: to begin
     execution.  If your program does not have a MAIN:, the compiler will
     report an error.

     Note that the line label MAIN does not mark the first line of your
     program's code; it only marks the starting point for execution of your
     program following reset.  You are free to place the line label MAIN
     anywhere in your file you deem appropriate.