[R] dates and time formats

[Mike R]

Is there a way in R to globally setup a default format for dates for all, or
nearly all, or just "many" R date/time-related functions?

For example, dates in library(chron) expects, by default, MDY with
forward-slash delimiters, whereas my habit  and my data sets tend to 
be YMD with dash delimiters, as in 2005-06-24 

Currently, I use the following practice:

dates("2005-06-24", format="y-m-d")
 
Is there a recommended documentation page that thoroughly describes
all the possible "environment" settings in addition to some such "date" 
setting? 

TIA,
Mike

       _                
platform i686-pc-linux-gnu
arch     i686             
os       linux-gnu        
system   i686, linux-gnu  
status                    
major    2                
minor    1.0              
year     2005             
month    04               
day      18               
language R