Full customization of output is achieved with replacing default formatting functions with user defined functions. There are two broad classes of functions, the conversion functions used for output units and elements of the Texinfo tree, and other formatting functions with diverse purposes, including formatting that are not based on tree elements (for example beginning and end of file formatting). Conversion functions are described in the next chapters.
This chapter describes how formatting functions are registered and basic formatting functions that can be used in diverse situations. More specific formatting functions are described later on together with information on specific output customization.
Most formatting functions are specific, with specific arguments, and a specific item formatted. They can be called for HTML formatting and may also be customized.
User defined functions associated with the formatting of special output units body (see Output Units) can be considered as formatting functions, but are registered especially (see Special Unit Body Formatting Functions).
The formatting functions are often called from functions that can be replaced by user-defined functions, therefore these functions may not be called if the replacement functions do not keep a similar operation.