Sorting a dataframe by multiple variables

["Thompson, Trevor" <tkt2@cdc.gov>]

I am trying to sort a dataframe by multiple columns using both ascending and
descending order.  It appears to me that sort.col only allows one order type
to be used.  I found this question in the archives, but there were no follow
up posts.  Any suggestions on how I might accomplish this?

Thanks!

-Trevor