Windows Restrictions on folder names

For some reasons, such as serial port placementProgramAfter a directory is named COM1, Windows automatically rolls it back to "new folder" or "New forlder ",

In the past, windows could not name files or folders by device name, while COM1 was the name of a device in the DOS era, not only COM1, but not any of the following names.
Con
Aux
COM1
Com2
Com3
Com4
LPT1
LPT1
Lpt2
Lpt3
Nul

You can create a directory as follows:
CMD --> md d: "Aux"

However, the Created directory cannot be opened from EXPLORER. You must use the UNC path to delete the directory.
Rd "." D: "Aux"