19.2.2.2 Special Characters in Pathname Components

Strings in pathname component values never contain special characters that represent separation between pathname fields, such as slash in Unix filenames. Whether separator characters are permitted as part of a string in a pathname component is implementation-defined; however, if the implementation does permit it, it must arrange to properly “quote” the character for the file system when constructing a namestring. For example,

 ;; In a TOPS-20 implementation, which uses ^V to quote 
 (NAMESTRING (MAKE-PATHNAME :HOST "OZ" :NAME "<TEST>"))
⇒  #P"OZ:PS:^V<TEST^V>"
NOT⇒ #P"OZ:PS:<TEST>"