<s>
HeaderDoc	B-Protocol
is	O
a	O
documentation	B-Protocol
generator	I-Protocol
developed	O
and	O
maintained	O
by	O
Apple	O
Inc	O
.	O
</s>
<s>
Using	O
specially	O
commented	O
source	O
code	O
files	O
as	O
input	O
,	O
HeaderDoc	B-Protocol
generates	O
documentation	O
for	O
the	O
code	O
in	O
HTML	B-Language
or	O
XML	B-Protocol
format	O
.	O
</s>
<s>
Syntax	O
for	O
HeaderDoc	B-Protocol
comment	O
tags	O
is	O
largely	O
similar	O
to	O
,	O
and	O
as	O
of	O
HeaderDoc	B-Protocol
version	O
8	O
,	O
supportive	O
of	O
Javadoc	B-Language
tags	O
.	O
</s>
<s>
HeaderDoc	B-Protocol
8.7	O
and	O
later	O
also	O
provides	O
partial	O
support	O
for	O
many	O
Doxygen	B-Language
tags	O
( @	O
form	O
only	O
,	O
and	O
must	O
conform	O
to	O
HeaderDoc	B-Protocol
tag	O
ordering	O
rules	O
)	O
.	O
</s>
<s>
Apple	O
's	O
HeaderDoc	B-Protocol
project	O
is	O
free	B-Application
,	O
open	B-Application
source	I-Application
software	I-Application
distributed	O
under	O
the	O
Apple	B-License
Public	I-License
Source	I-License
License	I-License
.	O
</s>
<s>
The	O
HeaderDoc	B-Protocol
tool	O
set	O
consists	O
of	O
the	O
main	O
utility	O
,	O
headerdoc2html	O
,	O
and	O
gatherheaderdoc	O
.	O
</s>
<s>
The	O
headerdoc2html	O
tool	O
generates	O
a	O
directory	O
of	O
either	O
HTML	B-Language
(	O
or	O
optionally	O
XML	B-Protocol
)	O
files	O
from	O
the	O
commented	O
source	O
files	O
specified	O
.	O
</s>
<s>
Apple	O
's	O
Xcode	B-Operating_System
development	O
environment	O
contains	O
features	O
designed	O
to	O
assist	O
the	O
process	O
of	O
creating	O
documentation	O
using	O
the	O
HeaderDoc	B-Protocol
syntax	O
and	O
tools	O
.	O
</s>
<s>
HeaderDoc	B-Protocol
has	O
the	O
following	O
core	O
features	O
:	O
</s>
<s>
C	B-Language
preprocessing	O
,	O
allowing	O
user-selected	O
#define	O
macros	O
to	O
alter	O
the	O
content	O
,	O
and	O
allowing	O
the	O
user	O
to	O
pass	O
command-line	O
flags	O
to	O
ignore	O
portions	O
of	O
the	O
input	O
.	O
</s>
<s>
Cross-platform	O
(	O
written	O
mostly	O
in	O
Perl	B-Language
)	O
.	O
</s>
<s>
The	O
HeaderDoc	B-Protocol
suite	O
also	O
includes	O
several	O
tools	O
that	O
may	O
be	O
used	O
independently	O
:	O
</s>
<s>
MPGL	O
—	O
a	O
set	O
of	O
tools	O
designed	O
to	O
simplify	O
creation	O
of	O
UNIX	B-Application
manual	O
pages	O
using	O
a	O
lightweight	O
XML	B-Protocol
syntax	O
consisting	O
of	O
a	O
subset	O
of	O
XHTML	O
plus	O
section	O
tags	O
,	O
parameter	O
tags	O
,	O
etc	O
.	O
</s>
<s>
HeaderDoc	B-Protocol
also	O
provides	O
a	O
bridging	O
tool	O
that	O
helps	O
generate	O
manual	O
pages	O
from	O
header	O
comments	O
for	O
functions	O
via	O
HeaderDoc	B-Protocol
's	O
XML	B-Protocol
output	O
mode	O
.	O
</s>
<s>
filtermacros.pl—a	O
tool	O
that	O
can	O
be	O
used	O
to	O
filter	O
out	O
sections	O
of	O
headers	O
based	O
on	O
C	B-Language
preprocessor	O
macros	O
.	O
</s>
<s>
As	O
of	O
HeaderDoc	B-Protocol
8.9	O
,	O
this	O
functionality	O
is	O
built	O
into	O
the	O
headerdoc2html	O
tool	O
itself	O
.	O
</s>
