I think variables in CM2.x is somewhat limited. It's Avaya's way to introduce the variables concept.
CM3.0 is when things become more interesting.
Below are some ideas you may have already thought about on tod, dow, doy for CM2.x.
TOD
===
Let, var=T type=tod
goto <we're closed step/vector> if T > 1700
the time that a call executes this vector step is compared with the string "1700". If the time is greater then the goto destination is executed next. This is a simple way to re-route based on the time of day regardless of the day.
To make this a bit more flexible, try comparing this 'T' variable with another variable that you can control either by changing via the SAT or by another vector. Let's say we introduce another variable 'A'
var=T type=tod
var=A type=collect scope=G (global) assignment=1700
goto <we're closed step/vector> if T > A
Add another VDN/vector that only priviledged users can access to change 'A'. It should contain the following step
collect 4 digits .. for A
Error checking can be done to ensure the value of 'A' is a valid military time (hhmm).
So let's say you want to change the closing hours, you can set 'A' to 1600 either by setting it via the "change variable" SAT command or by calling the above vector and entering in the digits 1600.
DOW
===
You can have a Wednesday Sale. So you always route those "Wednesday" (dow=4) calls to a certain "Wednesday" announcement?
DOY
====
This is one of the least useful in my opinion. It can be used up to February 28 for special days. For example Valentines day sales. Leap year get's in the way, so the days go off by 1 after the 28th. But wait until CM3.x, then it becomes valuable to calculate the weeks in the year, even if it's a leap year.
Again I think CM2.x is just an introduction, and isn't meant to be earth shattering.
But CM3.x is where Avaya starts making things interesting by allowing the setting of these variables.
tod, dow, and doy can be used in the SET command to timestamp when a certain vector step is executed, determine if a new week has occurred so you can re-route out-of-hour calls to a different on-call support tech, or reset other variables if it is a new day, a new week, or new year. You can even calculate the week number using the doy variable.
Hope this helps, or generates other thoughts.