NOTE(3EXT)						    Extended Library Functions							NOTE(3EXT)

NAME

       NOTE, _NOTE - annotate source code with info for tools

SYNOPSIS

       #include <note.h>

       NOTE(NoteInfo);

       or
       #include<sys/note.h>

       _NOTE(NoteInfo);

DESCRIPTION

       These  macros are used to embed information for tools in program source. A use of one of these macros is called an "annotation". A tool may
       define a set of such annotations which can then be used to provide the tool with information that would otherwise be unavailable  from  the
       source code.

       Annotations  should,  in general, provide documentation useful to the human reader. If information is of no use to a human trying to under-
       stand the code but is necessary for proper operation of a tool, use another mechanism for conveying that information to the tool (one which
       does  not  involve  adding  to the source code), so as not to detract from the readability of the source. The following is an example of an
       annotation which provides information of use to a tool and to the human reader (in this case, which data  are  protected  by  a	particular
       lock, an annotation defined by the static lock analysis tool lock_lint).

       NOTE(MUTEX_PROTECTS_DATA(foo_lock, foo_list Foo))

       Such  annotations  do  not represent executable code; they are neither statements nor declarations.  They should not be followed by a semi-
       colon. If a compiler or tool that analyzes C source does not understand this annotation scheme, then the tool will ignore the  annotations.
       (For such tools, NOTE(x) expands to nothing.)

       Annotations may only be placed at particular places in the source.  These places are where the following C constructs would be allowed:

	 o  a top-level declaration (that is, a declaration not within a function or other construct)

	 o  a declaration or statement within a block (including the block which defines a function)

	 o  a member of a struct or union.

       Annotations are not allowed in any other place.	For example, the following are illegal:

       x = y + NOTE(...) z ;
       typedef NOTE(...) unsigned int uint ;

       While  NOTE  and  _NOTE may be used in the places described above, a particular type of annotation may only be allowed in a subset of those
       places. For example, a particular annotation may not be allowed inside a struct or union definition.

   NOTE vs _NOTE
       Ordinarily, NOTE should be used rather than _NOTE, since use of _NOTE technically makes a program non-portable. However, it may be inconve-
       nient  to  use  NOTE  for this purpose in existing code if NOTE is already heavily used for another purpose.  In this case one should use a
       different macro and write a header file similar to /usr/include/note.h which maps that macro to _NOTE in the same manner.  For example, the
       following makes FOO such a macro:

       #ifndef _FOO_H
       #define _FOO_H
       #define FOO _NOTE
       #include <sys/note.h>
       #endif

       Public  header  files  which  span  projects  should use _NOTE rather than NOTE, since NOTE may already be used by a program which needs to
       include such a header file.

   NoteInfo Argument
       The actual NoteInfo used in an annotation should be specified by a tool that deals with program source (see the documentation for the  tool
       to determine which annotations, if any, it understands).

       NoteInfo must have one of the following forms:

	      NoteName
	      NoteName(Args)

       where NoteName is simply an identifier which indicates the type of annotation, and Args is something defined by the tool that specifies the
       particular NoteName. The general restrictions on Args are that it be compatible with an ANSI C tokenizer and that unquoted  parentheses	be
       balanced (so that the end of the annotation can be determined without intimate knowledge of any particular annotation).

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       note(4), attributes(5)

SunOS 5.10							    31 Dec 1996 							NOTE(3EXT)