Streamlined FTP Command Extensions is a proposal for 5 new FTP commands. I stress the word proposal, because it seems to have been abandoned, and would not progress to Internet Standard without a good deal of effort. That said, there was a decent amount of interest in at least some of the commands. I'm going to quote liberally from it for some of the descriptions.
REMOVE DIRECTORY ALL (RMDA) "removes a directory from the server and all of its contents including all files and subdirectories. The RMDA command is considered analogous to recursively deleting all files and directories contained in a given remote directory (including the directory itself) one at a time.
The primary advantage to using this command is the elimination of the additional commands usually required to perform the equivalent action. For directories containing a large number of files and subdirectories, using RMDA eliminates the overhead of querying for subdirectory listings. The end result is a more responsive operation for both the client and server. Depending on the content being deleted (files and subdirectories) this can be a very lengthy operation for the server."
DIRECTORY SIZE (DSIZ) returns the size of a directory and its contents.
"While a method already exists to retrieve similar information by recursively issuing the SIZE command as defined in [RFC3659] and tallying the results, the SIZE command returns the number of transfer octets for a specified file, which means that it considers the current data representation type in its calculated response."
AVAILABLE OCTETS (AVBL) tells the client how much free disk space there is "available to receive uploads in a specified remote directory for the logged in user."
Retrieve Thumbnail of Remote Image File (THMB) is used to get a thumbnail, or smaller version, of an image.
Client / Server Identification (CSID) lets the client and server provide details about what software they are running, such as name, version, vendor, and operating system, along with whether the underlying file system is case sensitive. It's similar to the "User-Agent" and "Server" HTTP header fields.
Would these new FTP commands be useful to you? Are some must haves, and others not that needed? I'd like to hear your thoughts.