The Open Group Base Specifications Issue 7
IEEE Std 1003.1, 2013 Edition
Copyright © 2001-2013 The IEEE and The Open Group

Typographical Conventions

The following typographical conventions are used throughout this standard. In the text, this standard is referred to as POSIX.1-2008, which is technically identical to The Open Group Base Specifications, Issue 7.

The typographical conventions listed here are for ease of reading only. Editorial inconsistencies in the use of typography are unintentional and have no normative meaning in POSIX.1-2008.




C-Language Data Structure


C-Language Data Structure Member


C-Language Data Type


C-Language External Variable


C-Language Function


C-Language Function Argument


C-Language Function Family


C-Language Header


C-Language Keyword


C-Language Macro with Argument


C-Language Macro with No Argument


C-Language Preprocessing Directive


Commands within a Utility

a, c

Conversion Specifier, Specifier/Modifier Character

%A, g, E


Environment Variable


Error Number


Example Output

Hello, World



Literal Character

'c', '\r'


Literal String



Optional Items in Utility Syntax

[ ]


<directory pathname>

Special Character



Symbolic Constant


Symbolic Limit, Configuration Value




#include <sys/stat.h>

User Input and Example Code

echo Hello, World


Utility Name


Utility Operand


Utility Option


Utility Option with Option-Argument

-w width

Note that:

  1. Conversion specifications, specifier characters, and modifier characters are used primarily in date-related functions and utilities and the fprintf() and fscanf() formatting functions.

  2. Unless otherwise noted, the quotes shall not be used as input or output. When used in a list item, the quotes are omitted. The literal characters <apostrophe> (also known as single-quote) and <backslash> are either shown as the C constants '\' and '\\', respectively, or as the special characters <apostrophe>, single-quote, and <backslash> depending on context.

  3. The style selected for some of the special characters, such as <newline>, matches the form of the input given to the localedef utility. Generally, the characters selected for this special treatment are those that are not visually distinct, such as the control characters <tab> or <newline>.

  4. Names surrounded by braces represent symbolic limits or configuration values which may be declared in appropriate headers by means of the C #define construct.

  5. Brackets shown in this font, "[ ]", are part of the syntax and do not indicate optional items. In syntax the '|' symbol is used to separate alternatives, and ellipses ("...") are used to show that additional arguments are optional.

Shading is used to identify extensions and options.

Footnotes and notes within the body of the normative text are for information only (informative).

Informative sections (such as Rationale, Change History, Application Usage, and so on) are denoted by continuous shading bars in the margins.

Ranges of values are indicated with parentheses or brackets as follows:

  1. (a,b) means the range of all values from a to b, including neither a nor b.

  2. [a,b] means the range of all values from a to b, including a and b.

  3. [a,b) means the range of all values from a to b, including a, but not b.

  4. (a,b] means the range of all values from a to b, including b, but not a.

Note: A symbolic limit beginning with POSIX is treated differently, depending on context. In a C-language header, the symbol POSIXstring (where string may contain underscores) is represented by the C identifier _POSIXstring, with a leading underscore required to prevent ISO C standard name space pollution. However, in other contexts, such as languages other than C, the leading underscore is not used because this requirement does not exist.

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