indicates an error, and an error code is stored in
.Va errno .
.Sh ERRORS
-.Fn Mkdir
+.Fn mkdir
will fail and no directory will be created if:
.Bl -tag -width Er
.\" ==========
.It Bq Er EIO
An I/O error occurred while reading from or writing to the file system.
.\" ==========
+.It Bq Er EISDIR
+The named file is the root directory.
+.\" ==========
.It Bq Er ELOOP
Too many symbolic links were encountered in translating the pathname.
This is taken to be indicative of a looping symbolic link.