select






select ‐ select keyword


 select expr,
   case expr1 then instructions1,
   case expr2 then instructions2,
   ...
   case exprn then instructionsn,
   [else instructions],
 end

Notes:
‐ The only constraint is that each "then"  keyword  must be
on the same line line as corresponding "case" keyword.
‐ The "keyword "then"  can be replaced by a carriage return
or a comma.


instructions1 are executed if expr1=expr, etc.


while %t do
  n=round(10*rand(1,1))
  select n
  case 0 then
    disp(0)
  case 1 then
    disp(1)
  else
    break
  end
end


if, while, for