Atsc working Draft Template

Case: Rating Blocked (
dcc_selection_type
 = 0x0D) 
If the 
dcc_selection_type
is specified to be of type 0x0D the term shall evaluate True if the current 
Virtual Channel is "blocked" as defined in CEA-766 [17] due to its Content Advisory and shall 
evaluate False otherwise. At the discretion of the DCCRR implementation, a timeout may be 
employed prior to the channel change to allow the viewer to override the blocked condition, for 
example by entering a parental password. Note that 
dcc_departing_request_descriptors
and 
dcc_arriving_request_descriptors
may be employed to provide a message to viewers that a channel-
blocked situation has arisen and that the DCCRR has switched to a new channel. 
Case: Return to Original Channel (
dcc_selection_type
 = 0x0F) 
If the 
dcc_selection_type
is specified to be of type 0x0F, and if the DCCRR is engaged in a DCC 
request of type Temporary Retune (
dcc_context
= 0), the DTV shall tune back to the channel from 
which it was previously directed (the previous DCC From Channel Number). 
Case: Viewer-Direct-Select (
dcc_selection_type
 = 0x20 – 0x23) 
If the 
dcc_selection_type
is specified to be of type 0x20 through 0x23, the DCCRR shall tune to the 
virtual channel specified in the DCC To Channel Number based upon the viewer’s selection of 
one of four “Viewer-Direct-Select” (VDS) function buttons (or equivalent). To correspond with 
textual or verbal prompting in the video program, the buttons shall be labeled or otherwise 
identified to the user as “A,” “B,” “C,” and “D.” For example, if the viewer chooses Viewer-
Direct-Select Button B and a DCC request has been defined for that button (
dcc_selection_type
value 
0x21), the DCCRR shall immediately switch to the DCC To Channel Number associated with the 
request. 
For 
dcc_selection_type
values 0x20 through 0x23, the 
dcc_selection_id
field is a 64-bit number that, 
when non-zero, enables a Viewer-Direct-Select “persistence” function. Value zero for the 
dcc_selection_id
field for 
dcc_selection_type
values 0x20 through 0x23 indicate that a persistence 
function for this button choice for this DCC request is not offered. 
61 

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ATSC A/65:2013 
Program and System Information Protocol 
7 August 2013 
6.7.3 
Viewer-Direct-Select Persistence 
The DCCRR shall implement a persistence function for the VDS DCC function. The persistence 
function allows the DCCRR to automatically take the same branch that was chosen by a prior VDS 
button selection when a new VDS opportunity arises. The following rules shall be followed: 
1) If in response to a VDS opportunity the user selects a button, the DCCRR shall record the 
value of that button’s 64-bit 
dcc_selection_id
(if non-zero). 
If a new VDS opportunity arises in which a 64-bit 
dcc_selection_id
value appears that corresponds 
to a recorded ID, the DCCRR shall use that branch as the default (the branch to be taken if no 
button is selected). 
2) If a new VDS opportunity arises in which a 64-bit 
dcc_selection_id
value appears that matches 
more than one recorded ID, the DCCRR shall take as the default branch the one associated 
with the most recently saved ID of those matching. 
3) Recorded IDs shall be saved in a stack in the DCCRR. The requirements regarding the size 
and organization of this stack are not specified and are left to the discretion of the 
implementer. 
The way in which the 64-bit VDS ID numbers are managed and assigned is outside the scope 
of this document. If broadcasters intend for them to work across different transmissions, 
coordination of their assignment will be required. If they want them not to work across to other 
broadcaster’s transmissions, appropriate steps should be taken to assure the 64 bit number is 
suitably random across the full 64-bit number space.