Alt0151

Alt0151 refers to a Windows Alt code used to insert the em dash character in many text applications. It is entered by holding the Alt key and typing 0151 on the numeric keypad, then releasing the keys. The resulting character is the em dash (—), a punctuation mark commonly used to indicate a strong break or to set off abrupt ends within sentences.

Technical notes: Alt codes rely on the Windows-1252 (Latin-1) code page on many systems. In this mapping, the decimal value 151 corresponds to the em dash, which in Unicode is U+2014. In other environments, Unicode input methods (such as typing U+2014 or using the HTML entity — or —) may be more reliable. Alt0151 may not work on non-Windows platforms, in programs that ignore legacy Alt codes, or when Num Lock is disabled or unavailable on the keyboard.

Limitations and variations: Some editors or international keyboard layouts do not support Alt codes or map 0151 differently, leading to no character or an unexpected symbol being inserted. Additionally, the same numeric sequence can produce different characters in non-Latin-1 code pages.

See also: Em dash, en dash, Unicode U+2014, Windows-1252, alternative methods for inserting punctuation such as HTML entities and other Unicode input techniques.