[R] confused on model.frame evaluation

[Erik Iverson]

<snip>
> 
> I'm sure it's not a bug, but could someone point to a thread or offer 
> some gentle advice on what's happening?  I think it's related to:
> 
> test <- data.frame(name1 = 1:5, name2 = 6:10, test = 11:15)
> eval(expression(test[c("name1", "name2")]))
> eval(expression(interco[c("name1", "test")]))

scratch that last one, obviously a typo was causing my confusion there! 
  The model.frame stuff remains a mystery to me though...