manifestation. The ISO/IEC 10646 (Unicode) International Standard defines character, or abstract character as "a member of a set of elements used for the organization, control, or representation of data". Unicode's definition supplements this with explanatory notes that encourage the reader to differentiate between characters, graphemes, and glyphs, among other things. Such differentiation is an instance of the wider theme of the separation of presentation and content. For example, the Hebrew letter aleph ("א") is often used by mathematicians to denote certain kinds of infinity (ℵ), but it is also used in ordinary Hebrew text. In Unicode, these two uses are considered different characters, and have two different Unicode numerical identifiers ("code points"), though they may be rendered identically. Conversely, the Chinese logogram for water ("水") may have a slightly different appearance in Japanese texts than it does in Chinese texts, and local typefaces may reflect this. But nonetheless in Unicode they are considered the same character, and share the same code point. The Unicode standard also differentiates between these abstract characters and coded characters or encoded characters that have been paired with numeric codes that facilitate their representation in computers. Combining character The combining character is also addressed by Unicode. For instance, Unicode allocates a code point to each of 'i ' (U+0069), the combining diaeresis (U+0308), and 'ï' (U+00EF). This makes it possible to code the middle character of the word 'naïve' either as a single character 'ï' or as a combination of the character with the combining diaeresis: (U+0069 LATIN SMALL LETTER I + U+0308 COMBINING DIAERESIS); this is also rendered as 'ï '. These are considered canonically equivalent by the Unicode standard. char A char in the C programming language is a data type with the size of exactly one byte, which in turn is defined to be large enough to contain any member of the "basic execution character set". The exact number of bits can be checked via macro. By far the most common size is 8 bits, and the POSIX standard requires it to be 8 bits. In newer C standards char is required to hold UTF-8 code units which requires a minimum size of 8 bits. A Unicode code point may require as many as 21 bits. This will not fit in a char on most systems, so more than one is used for some of them, as in the variable-length encoding UTF-8 where