Nothing else was changed on the tables. I have it down to 1,500. Bits on Demand Protocol implementors have suffered from the erroneous opinion that implementing FTP ought to be a small and trivial task. Modern FTP evolved from an era of radically diverse systems. There are historic reasons it accumulated a welter of commands, transfer modes, and data representations.
File systems are where the trouble begins.
Now, there s metadata about organization, access control, and data representation. Just as Telnet faced down the challenge of connecting N terminal types with a single Network Virtual Terminal, FTP introduced an NVFS to bridge differing filing hierarchies, data types, file structures, and transfer modes. First, pathnames are presumed relative by default, disambiguating requests. Second, replies can encode the current path in machine-readable form, so clients just store an opaque string. File representation was the knottier part of NVFS and took years to sort out into two axes.