The DELIVERY TIMEOUT extension (Extension Header Type 0x02) is a Track Extension. It expresses the publisher's DELIVERY_TIMEOUT for a Track (see Section 9.2.2.2).
DELIVERY_TIMEOUT, if present, MUST contain a value greater than 0. If an
endpoint receives a DELIVERY_TIMEOUT equal to 0 it MUST close the session with
PROTOCOL_VIOLATION.
If unspecified, the subscriber's DELIVERY_TIMEOUT is used. If neither endpoint specified a timeout, Objects do not time out.
11.1.1. MAX CACHE DURATION
The MAX_CACHE_DURATION extension (Extension Header Type 0x04) is a Track Extension.
It is an integer expressing the number of milliseconds an Object can be served from a cache. If present, the relay MUST NOT start forwarding any individual Object received through this subscription or fetch after the specified number of milliseconds has elapsed since the beginning of the Object was received. This means Objects earlier in a multi-object stream will expire earlier than Objects later in the stream. Once Objects have expired from cache, their state becomes unknown, and a relay that handles a downstream request that includes those Objects re-requests them.
If the MAX_CACHE_DURATION extension is not sent by the publisher, the Objects can be cached until implementation constraints cause them to be evicted.
11.1.1.1. DEFAULT PUBLISHER PRIORITY
The DEFAULT PUBLISHER PRIORITY extension (Extension Header Type 0x0E) is a Track Extension that specifies the priority of a subscription relative to other subscriptions in the same session. The value is from 0 to 255 and lower numbers get higher priority. See Section 7. Priorities above 255 are invalid. Subgroups and Datagrams for this subscription inherit this priority, unless they specifically override it.
A subscription has Publisher Priorty 128 if this extension is omitted.
11.1.1.2. DEFAULT PUBLISHER GROUP ORDER
The DEFAULT_PUBLISHER_GROUP_ORDER extension (Extension Header Type 0x22) is a Track Extension.
It is an enum indicating the publisher's preference for prioritizing Objects
from different groups within the
same subscription (see Section 7). The allowed values are Ascending (0x1) or
Descending (0x2). If an endpoint receives a value outside this range, it MUST
close the session with PROTOCOL_VIOLATION.
If omitted, the publisher's preference is Ascending (0x1).
11.1.1.3. DYNAMIC GROUPS
The DYNAMIC_GROUPS Extension (Extension Header Type 0x30) is a Track Extension.
The allowed values are 0 or 1. When the value is 1, it indicates
that the subscriber can request the Original Publisher to start a new Group
by including the NEW_GROUP_REQUEST parameter in PUBLISH_OK or REQUEST_UPDATE
for this Track. If an endpoint receives a value larger than 1, it MUST close
the session with PROTOCOL_VIOLATION.
If omitted, the value is 0.