I get this error:
* /inc: invalid parameters

To reproduce:
//var %a = 1 | while (%a != 5) !inc %a

How ever this works:
//var %a = 1 | while (%a != 5) inc %a
//var %a = 1 | while (%a != 5) { | !inc %a }

Win XP version 6.16 and 6.15 failed.