To keep track of IF...ENDIF, or indeed any other block statements which themselves could be nested (such as FOR...NEXT, or WHILE...WEND) it's convenient to indent the code for every block statement. The compiler ignores surplus indents and it makes it more human readable when looking at the code. Example...
Code:
Start:
	'
	'	Set Dual-Colour LED
	'	-------------------
	If PowerOn=1 then
		High PowerOnLEDGreen
		Low PowerOnLEDRed
		If BatteryLow=0 then
			High PowerOnLEDRed
			Low PowerOnLEDGreen
			endif
		endif
	Gosub ScanKeyboard
	Goto DoCleverStuff
This way you can easily track the preceeding IF statement associated with any corresponding ENDIF by just following the indented block.

Why is Yoda wearing rubber gloves whilst doing hand-puppet Rabbit impressions?...