2.2.4.9 Path Names
A Path Name is a string that contains the file name, or full path and file name, including subdirectories, for the identified file. The string MUST permit white space and MUST NOT be empty.
If the path name string identifies a network-addressable file, it MUST be a DNS, NetBIOS, IPv4, or universal naming convention (UNC) name, or it SHOULD be an IPv6 name.<217> The string SHOULD be of the form "\\ServerName\ShareName" and MUST identify a unique shared folder on the machine.
The pattern followed by path name strings of local files SHOULD be specified by the implementation.<218>
An implementation SHOULD restrict the length of path name strings.<219>
For further information on DNS names, see [RFC819] section 2. NetBIOS names are specified in [RFC1001] section 14.