rem S-BASIC of course allows traditional BASIC-style comments

comment
  In addition to the single-line REM statement, S-BASIC
  also supports multiline comments using COMMENT...END.
  Note that the terminating END must be the first token on
  a line of its own.
end

comment
  When declaring a group of variables, S-BASIC allows
  a semi-colon, instead of the normal comma, as a separator,
  in which event an explanatory comment can follow the
  semi-colon and is ignored by the compiler.
end

var n   ; number of payments over life of loan
    ppy ; payments per year
    apr ; annual interest rate as a decimal
    amt ; principal amount of loan
    pmt ; amount of periodic payment
        = real

comment
   Finally, although statements in S-BASIC are normally terminated
   by an end-of-line, any logical statement can be continued on to
   the following physical line with a backslash, in which event
   anything after the backslash is ignored and can be used for
   a comment.
end

if amt = 0 then      \ user forgot to enter a value
   print "Must specify a loan amount!"
end