Accessing System Variables

How do I access System Variables?  Specifically, I want to add a year and month seperately but those variables are not listed in the Variables pod (a bunch of other things are, long dates and so on).

I can add them as User Variables, setting them up as <$year> and <$monthname>, but that doesn't work either (the output is "<$year" and "<$monthname" respectively).

I can import the variables from another document, but I shouldn't have to.  They have got to be in there someplace, but where?  How can I get to them without importing a bunch of duplicate variables from other docs?

Thanks in advance.

dc10