U009F

U009F is a designation that is commonly associated with the Unicode code point U+009F, a non-printing control character within the C1 control set. In Unicode, U+009F is defined as the Application Program Command (APC) control code, which has historically been used to carry application-specific commands within data streams. It does not correspond to a visible symbol and typically has no graphical representation in standard text.

In encoding terms, U+009F is part of the C1 controls and is encoded in UTF-8 as the two-byte sequence 0xC2 0x9F. In legacy character encodings that separate C1 controls from printable characters, U+009F remains a non-printing control. The APC designation reflects its role in signaling application-defined processing rather than rendering text. Because APC is a control code, it is generally ignored by ordinary text rendering and is often stripped or preserved only within specialized communication or formatting contexts.

Context and usage vary by standard. Within ISO/IEC 6429 (ECMA-48) and related specifications, APC is one of several C1 controls used to manage control sequences in data streams or terminal communications. In modern software, direct handling of APC is rare outside of low-level protocol implementations, data capture, or terminal emulation that must preserve control information.

See also: U+009F, APC (Application Program Command), C1 controls, ISO/IEC 6429, Unicode encoding.