even on NTFS partitions? Why is that?
In addition to Win32 filenames, NTFS supports also DOS and POSIX ones by the mechanism of filename namespaces. This way, a file not only can have colons or backslashes in its name, but it may even have multiple names.
You may have seen the DOS filenames e.g. on the command line, like the
MICROS~1 below (or the commonly seen
PROGRA~1 name for
Program Files in the root directory of
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.
C:\Users\User>cd c:\Program Files
c:\Program Files>dir /x
Volume in drive C has no label.
Volume Serial Number is E4FC-4AD7
Directory of c:\Program Files
01/16/2020 10:13 PM <DIR> .
01/16/2020 10:13 PM <DIR> ..
05/26/2020 04:39 PM <DIR> 7-Zip
07/14/2009 06:20 AM <DIR> COMMON~1 Common Files
11/21/2010 10:16 AM <DIR> DVDMAK~1 DVD Maker
11/21/2010 10:06 AM <DIR> INTERN~1 Internet Explorer
11/21/2010 10:16 AM <DIR> MICROS~1 Microsoft Games
01/16/2020 10:14 PM <DIR> MINGW-~1 mingw-w64
07/14/2009 08:32 AM <DIR> MSBuild
07/14/2009 08:32 AM <DIR> REFERE~1 Reference Assemblies
11/21/2010 10:06 AM <DIR> WINDOW~3 Windows Defender
11/21/2010 10:16 AM <DIR> WI0FCF~1 Windows Journal
11/21/2010 10:06 AM <DIR> WINDOW~1 Windows Mail
11/21/2010 10:06 AM <DIR> WI54FB~1 Windows Media Player
07/14/2009 08:32 AM <DIR> WINDOW~2 Windows NT
11/21/2010 10:06 AM <DIR> WINDOW~4 Windows Photo Viewer
11/21/2010 06:31 AM <DIR> WIBFE5~1 Windows Portable Devices
11/21/2010 10:06 AM <DIR> WI4223~1 Windows Sidebar
0 File(s) 0 bytes
18 Dir(s) 5,582,016,512 bytes free
In the above directory listing, the two namespaces of files are listed next to each other. The entries whose Win32 names which don't conflict with DOS, don't have a DOS name.
windows_names option mentioned in another answer, the Linux NTFS driver
ntfs-3g uses the POSIX namespace to name the files it creates.