Where are usages like "== 2L" documented?

Gurus:

I keep seeing other people?s code that contain ideas like

If (x == 2L)
X[-1L]
X - 1L

I have some idea of what?s going on, but where is the use of  
concepts like
?2L? documented?

Not sure where exactly, and it would depend on where you learned R.  
The integer data type information and notation should have been found  
among the material where you learned about "numeric", "character",  
"logical", .... that sort of basic notion.

David Winsemius, MD
Heritage Laboratories
West Hartford, CT