[R] index question

[Jeffrey Stratford]

Thanks for those on the list that answered my previous question.  I'm
just about where I need to be (looking at output).  

In the hier.part documentation there is a line env <- urbanwq[,2:8].  

This means use rows 2 through 8 in the data frame "urbanwq", right? 
What does the comma represent?  If one wasn't using column headers would
this be necessary?

Thanks,

Jeff



****************************************
Jeffrey A. Stratford, Ph.D.
Postdoctoral Associate
331 Funchess Hall
Department of Biological Sciences
Auburn University
Auburn, AL 36849
334-329-9198
FAX 334-844-9234
http://www.auburn.edu/~stratja