Alternate Data Streams
From Linux NFS
The NFSv4 protocol includes "named attributes" (RFC 7530 section 5.3). Microsoft uses the term "Alternate Data Streams" for a similar NTFS feature. (See, for example, https://blogs.technet.microsoft.com/askcore/2013/03/24/alternate-data-streams-in-ntfs/).
They are sometimes confused with the Linux "extended attribute" feature.