[R] What does class "call" mean? How do I make class "formula" into a "call"?

[StellathePug]

Hello R Users! 
I have a list called "tabs" that I would like to have the same structure as
my list "eqSystem." The two look like they have the same structure but they
are different because when I look at their attributes, class(eqSystem[[1]])
is "call" but class(tabs[[1]]) is "formula". I want to have class(tabs[[1]])
as a call too. 

So what does "call" mean? 

And how do I make an object of class "formula" be of class "call"? 
Thank you so much!!!--Rita


> class(tabs)
[1] "list"
> class(tabs[1])
[1] "list"
> class(tabs[[1]])
[1] "formula"> class(eqSystem)
[1] "list"
> class(eqSystem[1])
[1] "list"
> class(eqSystem[[1]])
[1] "call"

Rita
=====================================
"If you think education is expensive, try ignorance."--Derek Bok

--
View this message in context: http://r.789695.n4.nabble.com/What-does-class-call-mean-How-do-I-make-class-formula-into-a-call-tp3623733p3623733.html
Sent from the R help mailing list archive at Nabble.com.