See the files in the doc directory for documentation about SYSLINUX:
syslinux.txt - Usage instructions; manual.
distrib.txt - For creators of Linux distributions.
pxelinux.txt - Documentation specific to PXELINUX.
isolinux.txt - Documentation specific to ISOLINUX.
extlinux.txt - Documentation specific to EXTLINUX.
menu.txt - About the menu systems.
usbkey.txt - About using SYSLINUX on USB keys.
comboot.txt - About the extension API.
memdisk.txt - Documentation about MEMDISK.
Also see the files:
NEWS - List of changes from previous releases.
TODO - About features planned for future releases.
COPYING - For the license terms of this software.
SYSLINUX now builds in a Linux environment, using nasm. You need nasm
version 0.98.39 or later to build SYSLINUX from source. See
http://nasm.sf.net/ for information about nasm.
There is now a mailing list for SYSLINUX. See the end of syslinux.txt
for details.
SYSLINUX is:
Copyright 1994-2010 H. Peter Anvin et al - All Rights Reserved
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, Inc., 53 Temple Place Ste 330,
Boston MA 02111-1307, USA; either version 2 of the License, or
(at your option) any later version; incorporated herein by reference.