<s>
Hypertext	B-Protocol
Caching	I-Protocol
Protocol	I-Protocol
(	O
abbreviated	O
to	O
HTCP	B-Protocol
)	O
is	O
used	O
for	O
discovering	O
HTTP	B-Protocol
caches	O
and	O
cached	O
data	O
,	O
managing	O
sets	O
of	O
HTTP	B-Protocol
caches	O
and	O
monitoring	O
cache	O
activity	O
.	O
</s>
<s>
All	O
multi-octet	O
HTCP	B-Protocol
protocol	O
elements	O
are	O
transmitted	O
in	O
network	O
byte	O
order	O
.	O
</s>
<s>
Headers	O
must	O
be	O
presented	O
with	O
the	O
CRLF	O
line	O
termination	O
,	O
as	O
in	O
HTTP	B-Protocol
.	I-Protocol
</s>
<s>
Any	O
hostnames	B-Protocol
specified	O
should	O
be	O
compatible	O
between	O
sender	O
and	O
receiver	O
,	O
such	O
that	O
if	O
a	O
private	O
naming	O
scheme	O
(	O
such	O
as	O
HOSTS.TXT	O
or	O
NIS	O
)	O
is	O
in	O
use	O
,	O
names	O
depending	O
on	O
such	O
schemes	O
will	O
only	O
be	O
sent	O
to	O
HTCP	B-Protocol
neighbors	O
who	O
are	O
known	O
to	O
participate	O
in	O
said	O
schemes	O
.	O
</s>
<s>
Raw	O
addresses	O
(	O
dotted	O
quad	O
IPv4	B-Protocol
,	O
or	O
colon-format	O
IPv6	B-Protocol
)	O
are	O
universal	O
,	O
as	O
are	O
public	O
DNS	B-Protocol
names	I-Protocol
.	O
</s>
<s>
UDP	B-Protocol
must	O
be	O
supported	O
.	O
</s>
<s>
HTCP	B-Protocol
agents	O
must	O
not	O
be	O
isolated	O
from	O
network	O
failures	O
and	O
delays	O
.	O
</s>
<s>
An	O
HTCP	B-Protocol
agent	O
should	O
be	O
prepared	O
to	O
act	O
in	O
useful	O
ways	O
when	O
no	O
response	O
is	O
forthcoming	O
,	O
or	O
when	O
responses	O
are	O
delayed	O
or	O
reordered	O
or	O
damaged	O
.	O
</s>
<s>
TCP	B-Protocol
is	O
optional	O
and	O
is	O
expected	O
to	O
be	O
used	O
only	O
for	O
protocol	O
debugging	O
.	O
</s>
<s>
The	O
IANA	O
has	O
assigned	O
port	O
4827	O
as	O
the	O
standard	O
TCP	B-Protocol
and	O
UDP	B-Protocol
port	O
number	O
for	O
HTCP	B-Protocol
.	O
</s>
<s>
An	O
HTCP	B-Protocol
Message	O
has	O
the	O
following	O
general	O
format	O
:	O
</s>
<s>
|	O
DATA	O
|	O
HTCP	B-Protocol
message	O
(	O
varies	O
per	O
major	O
ver	O
.	O
</s>
