Universal naming convention (UNC) paths are used in Microsoft Windows to access network resources. They have a special format defined by Microsoft.
Microsoft’s Definition of UNC Path
https://learn.microsoft.com/en-us/dotnet/standard/io/file-path-formats#unc-paths UNC Path (Microsoft documentation)
(Universal Naming Convention) A standard for identifying servers, printers and other resources in a network, which originated in the Unix community. A UNC path uses double slashes or backslashes to precede the name of the computer. The path (disk and directories) within the computer are separated with a single slash or backslash, as in the following examples. Note that in the DOS/Windows example, drive letters (c:, d:, etc.) are not used in UNC names.