Xlib --- C Language X Interface uses the following conventions:
This HTML version of the manual uses formatting conventions that are slighty different of the original (troff) manual:
Global symbols are either printed in bold, either hyperlinked or both. Functions name are printed in bold, suffixed with () and hyperlinked to their definition page. Symbols define in include files are rendered with a bold typeface. Structure names are printed in regular type and are hyperlinked to their definition. When declared and defined, function arguments are printed in bold, and also in the following explanatory text.
Each function is introduced by a general discussion that distinguishes it from other functions. The function declaration itself follows, and each argument is specifically explained. Although ANSI C function prototype syntax is not used, Xlib header files normally declare functions using function prototypes in ANSI C environments. General discussion of the function, if any is required, follows the arguments. Where applicable, the last paragraph of the explanation lists the possible Xlib error codes that the function can generate. For a complete discussion of the Xlib error codes, see "Using the Default Error Handlers".
To eliminate any ambiguity between those arguments that you pass and those that a function returns to you, the explanations for all arguments that you pass start with the word specifies or, in the case of multiple arguments, the word specify. The explanations for all arguments that are returned to you start with the word returns or, in the case of multiple arguments, the word return. The explanations for all arguments that you can pass and are returned start with the words specifies and returns.
Any pointer to a structure that is used to return a value is designated as such by the _return suffix as part of its name. All other pointers passed to these functions are used for reading only. A few arguments use pointers to structures that are used for both input and output and are indicated by using the _in_out suffix.