Why a folder can't be renamed to

There are certain words that have predefined meanings called Reserved Words.

Some of the more common are:
CON - The display monitor
PRN - Default value is LPT1
LPT1-LPT3
AUX - Serial port 1 (COM1)
COM1-COM4
NUL

Oh yes, don't use these words for User Logons either.

When you get into specific applications, there are other Reserved Words that are specific to the particular application. For example, the JET 4.0 engine has a list of over 100 Reserved Words. The A's look like this;

ABSOLUTE ACTION ADD ADMINDB ALL ALLOCATE ALPHANUMERIC ALTER AND ANY ARE AS
ASC ASSERTION AT AUTHORIZATION AUTOINCREMENT AVG

jdg

Tthis is the second time I've heard somebody ask this; the other time being in Q/A. Maybe you asked it there too; I can't be bothered to check right now. :)

I'm curious. Why the interest in naming a folder con, aux or nul?

you know that we cant create a folder named CON, NUL, COM1, COM2, COM3, LPT1, LPT2, LPT3,COM1 to COM9 and LPT1 to LPT9....
in any of the windows operating system.
try with this.

but here is the master mind.............
i found one method to create the folders with these reserverd system names.
here is the solution to create the folder named con and other system variables.
1) go to run dialog.
2) type cmd/command (command prompt gets opened)
3) go to root directory like C:\ or D:\ etc
4) type md\\.\\c:\\con ....(here is done)
5) check the folder on the respected drive.