U000F

U+000F, commonly written as U000F in some contexts, is the Unicode code point for the control character known as Shift In (SI). It is one of the C0 control codes in ASCII and Unicode and has no printable glyph. Its code point number is 15 in decimal.

Historically, Shift In, together with Shift Out (SO, U+000E), was used on teletypewriters and early computing systems to switch between alternate character sets within a single 7-bit code stream. In practice, an SI sequence would activate a different graphic or locale-specific set, with SO returning to the original. In later standards such as ISO/IEC 2022, the approach to designating character sets evolved to G0/G1 and GL/GR, but U+000F remains defined as a control character for compatibility.

In modern text processing, Shift In is rarely used and most software treats U+000F as a non-printing control character that may be ignored or discarded. When encountered in a text file, its presence is usually transparent to casual users, though it can affect legacy systems or data interchange that rely on older 7-bit control semantics. Encoding-wise, U+000F encodes as 0x0F in UTF-8 and as 0x000F in UTF-16. It belongs to the Unicode General Category Cc (Other Control).