ASCII 28 — FS

File Separator (FS) is one of four hierarchical information separator characters in ASCII, designed to structure data into nested levels. FS marks the highest-level boundary — between files in a data stream. While largely supplanted by modern file systems, databases, and structured formats like JSON and XML, the four ASCII separator characters (FS, GS, RS, US) represent a remarkably early attempt at self-describing hierarchical data structures. Some Unix tools still support ASCII separators for unambiguous field delimiting.

Control characters were defined in the original 1963 ASCII standard to manage telecommunications equipment and terminal devices. Unlike printable characters representing visible symbols, control codes perform actions: initiating transmissions, acknowledging received data, triggering device alerts, and structuring information hierarchically. Of ASCII's 128 code points, 33 are designated as control characters (codes 0–31 plus 127), reflecting the standard's deep roots in telegraphy and serial communication systems. While most control codes have fallen out of daily use, several remain essential to modern computing workflows.

In the ASCII encoding table, File Separator is assigned code point 28 in decimal (0x1C hexadecimal, 034 octal, 00011100 binary). The 7-bit ASCII standard, first published in 1963 by the American Standards Association, defines exactly 128 characters that remain the foundation of text encoding systems worldwide. UTF-8, the dominant encoding on the modern web, is fully backward compatible with ASCII — every ASCII character is encoded as the identical single byte in UTF-8, guaranteeing that File Separator works reliably across all operating systems, programming languages, and internet protocols.