Section 3 of the manual describes all library functions excluding the library
functions (system call wrappers) described in section 2,
which implement system calls.
Many of the functions described in the section are part of the
Standard C Library
Some functions are part of other libraries (e.g.,
the math library,
or the real-time library,
in which case the manual page will indicate the linker
option needed to link against the required library
for the aforementioned libraries).
In some cases,
the programmer must define a feature test macro in order to obtain
the declaration of a function from the header file specified
in the man page SYNOPSIS section.
In such cases, the required macro is described in the man page.
For further information on feature test macros, see
Certain terms and abbreviations are used to indicate Unix variants
and standards to which calls in this section conform.
Authors and Copyright Terms
Look at the header of the manual page source for the author(s) and copyright
Note that these can be different from page to page!