This is the explanation from Microsoft.....
Windows has a maximum PATH length of 260 characters, so that includes
the drive letter (+ colon and backslash) folder and sub-folder names and
Under Windows using the NTFS file system file and folder names may be up
to 256 characters long.
The following characters are invalid as file or folder names on Windows
/ ? < > \ : * | " and any character you can type with the Ctrl key.
In addition to the above illegal characters the caret ^ is also not
permitted under Windows Operating Systems using the FAT file system.
In addition to these characters, the following conventions are also illegal:
Placing a space at the end of the name
Placing a period at the end of the name
The following file names are also reserved under Windows:
com1, com2, com3, com4, com5, com6, com7, com8, com9, lpt1, lpt2,
lpt3, lpt4, lpt5, lpt6, lpt7, lpt8, lpt9, con, nul, and prn