Few question about the state machine explain of eight leds and eight push buttons present on this web.

what does the following means and where it is used i also saw this in the state machine explain of eight switches

LENGTH EQU $-MESSAGE ; what does $ means here $ using means stay on the same line. (taken from scott mackenzine book)

STATE_CNT EQU ($-STATE_TABLE)/2 ; number of states
the above is in the state machine example.

In the start of the code at PWR_UP low is send to bits and bytes where the switch status and state is to be placed using indirect addressing wy simply zero is not moved on the bytes ?

In MAIN_LOOP: MOV A, SwitchNo ; is the switch number to be processed.
on next line ADD A,#SwitchStates ; this for fetching the state for that switch , can we use MOV A,#SwitchStates ?

the table of SWT_MSK telling the controller that there is High on the switch to be processed or something else?

5 sec counter is equated to 5*100 can ASM51 read this as 5 seconds counter or what it suppose to mean, explain the 5 second counter & 10 msec relation shown in teh start of state 1 ?

How the counter State 1 works specially the part where CLR C and RLC A is used ? where in comments it is written make*2 word type index to counter table

In State 2 ADD A,#Switchcounters+1 offset what does this means i have gone through scott's book but no clue.

what is the function of CALL_Table ?