Editing SS13 for experienced programmers (section)

==== [http://www.byond.com/members/?command=reference&path=var Predefined variables] ====
There is a lot of predefined variables for objects in BYOND, but the most important are:
*'''[http://www.byond.com/members/?command=reference&path=proc%2Fvar%2Fsrc src]''' - a variable equal to the object containing the proc or verb. It is defined to have the same type as that object. (Similar to "this" in Java or C++)
*'''[http://www.byond.com/members/?command=reference&path=proc%2Fvar%2Fusr usr]''' - a mob variable (var/mob/usr) containing the mob of the player who executed the current verb, or whose action ultimately called the current proc. '''A good rule of thumb is to never put usr in a proc.''' If src would not be the correct choice, it is better to send another argument to your proc with the information it needs.
*'''[http://www.byond.com/members/?command=reference&path=proc%2Fvar%2Fargs args]''' - a list of the arguments passed to the proc or verb.
*'''[http://www.byond.com/members/?command=reference&path=datum%2Fvar%2Fvars vars]''' - a list of object variables. If the variable name is used as an index into the list, the value of that variable is accessed.

For more SS13 specific variables see [[#SS13 common variable meanings|SS13 common variable meanings]]