Variables

global variables (enabled when awk->opt & XP_AWK_OPT_VARDCL)

	global x;
	global x, y;

local variables  (enabled when awk->opt & XP_AWK_OPT_VARDCL)

	local x;
	local x, y;

function arguments (enabled always) 

	function funca (x, y)


local variables in function declaration  (enabled when awk->opt & XP_AWK_OPT_FUNCLOCAL)

	function funca (x, y,		v1, v2)


variables without any declarations (enabled when awk->opt & XP_AWK_OPT_NAMEDVAR)

	x = 10; // x is put into the global hash table.


Optimization

constant folding
	2 * 10  => 20

loop 
	remove while (0) { ... } 
	
if
	remove if (0) {}
	use else_part only