Protected folders in Windows OS , You can't use them to name a Folder

[TheGreatOne]

Microsoft Operating Systems does not allow its users to create folders with the following names :

CON, PRN, AUX,CLOCK$, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8 & LPT9

Among these CON is more popular

What are they?

• CON Keyboard and display
  
  
• PRN System list device, usually a parallel port
  
  
• AUX Auxiliary device, usually a serial port
  
  
• CLOCK$ - (FOR WINNT) System real-time clock
  
  
• NUL Bit-bucket device
  
  
• COM1 First serial communications port
  
  
• COM2 Second serial communications port
  
  
• COM3 Third serial communications port
  
  
• COM4 Fourth serial communications port
  
  
• LPT1 First parallel printer port
  
  
• LPT2 Second parallel printer port
  
  
• LPT3 Third parallel printer port

APPLIES TO

• Microsoft MS-DOS 2.11 Standard Edition
  
  
• Microsoft MS-DOS 3.1
  
  
• Microsoft MS-DOS 3.2 Standard Edition
  
  
• Microsoft MS-DOS 3.21 Standard Edition
  
  
• Microsoft MS-DOS 3.3 Standard Edition
  
  
• Microsoft MS-DOS 3.3a
  
  
• Microsoft MS-DOS 4.0 Standard Edition
  
  
• Microsoft MS-DOS 4.01 Standard Edition
  
  
• Microsoft MS-DOS 5.0 Standard Edition
  
  
• Microsoft MS-DOS 5.0a
  
  
• Microsoft MS-DOS 6.0 Standard Edition
  
  
• Microsoft MS-DOS 6.2 Standard Edition
  
  
• Microsoft MS-DOS 6.21 Standard Edition
  
  
• Microsoft MS-DOS 6.22 Standard Edition

REASON

Back in the DOS days, "con" had a special meaning. It referred to the console, and allowed you to treat it like any other file. For example, you you might create a new text file by typing copy con new.txt. Then you could enter your text and hit ^Z when finished.

The thing is, you can still do that. Therefore, as far as the file system is concerned there is already an object out there named con.

Likewise the other files(Serial ports, Printer ports, System clock etc) as above listed, shall not be renamed..


NOTE

Still you can rename any folder with the above names through DOS, which may harm your system basic functions. Beware !

[TheGreatOne]

Still there some methods by using them you can create folder which will look like them , for example see one method as below :

1. While naming the folder, type 'CON' and type 255 simultaneously holding the ALT button.
   
   

   'CON' + (ALT (holding) + '255').

By using this process you can create a folder CON but including with the Invisible character .

To know the full usage of invisible character refer this : Use Invisible Character in any text editor !