[syslinux] few question

[pierre-yves.verdon]

hi,
i'm wondering aboot the option "vendor-class identifier" what means 
these two number? i have actually us it in my dhcpd.conf, and all is 
working, but i don't know what it mean....
if substring (option vendor-class-identifier, 0, 3) = "PXE"

i have the same question for the "option vendor-encapsulated-options" ?

this is just because, i just read a ltsp pxe howto and that both of 
these option have different parameter

for example:
option vendor-encapsulated-options 3c:09:45:74:68:65:72:62:6f:6f:74:ff;

and I use:
option vendor-encapsulated-options 
09:0f:80:00:0c:4e:65:74:77:6f:72:6b:20:62:6f:6f:74:0a:07:00:50:72:6f:6d:70:74:06:01:02:08:03:80:00:00:47:04:80:00:00:00:ff;

i suppose the vendor-encapsulated-options identify the network device, 
am i right?

http://www.ltsp.org/documentation/pxe.howto.html

-- 
pierre-yves