The if statement creates the branches and switches of your Xtscript
[...] = optional ... = your value
if not ... or ...
...
[else
...]
endif
<!--parser:xtscript-->
# 2 random numbers
var $x = call mt_rand $min=1;$max=100
var $y = call mt_rand $min=1;$max=100

# If not ... Or ...
# simulates $x > 50 and $y < 50
if not $x >= 50 or $y > 50
  print \$x is less than 50 or \$y is more than 50<hr />
else
  print \$x is more than 50 \$y is less than 50<hr />
endif

print \$x=$x \$y=$y<br />

<!--/parser:xtscript-->
Show in textarea
Reload
$x is less than 50 or $y is more than 50
$x=21 $y=53