Editing Radio Data System (section)

==== Shared structure ====
Block 1 always contains the 16-bit program identifier. The first 11 bits (bits 15–5) of block 2 are also the same in all groups.

The first 4 bits (bits 15–11) of block 2 are the "group type code", which describe the interpretation of the remaining data. Each group type comes "A" and "B" variants, distinguished by the fifth "B" bit (bit 10): If B=0, then the group is 0A through 15A, and contains 5+16+16 = 37 bits of data. If B=1, block 2 contains a PI code (and is encoded with offset word C′), the group is one of 0B through 15B, and contains 21 bits of data.

Within Block 1 and Block 2 are structures that will always be present in both group versions, for fast and responsive identifications. The first block of every group, will always be the program identification code. The second block dedicates the first 4 bits for Application/Group Type.
{| class="wikitable"
|-
|
|Block 1
| colspan="5" |Block 2
|-
|Block Meaning
|Program Identification Code
|GTYPE
|B0
|TP
|PTY
|''varies''
|-
|bit notation per block
|b15 — b0
|b15–b12
|b11
|b10
|b9–b5
|b4–b0
|-
|Fixed Meaning Per Group?
|Yes
|Yes
|Yes
|Yes
|Yes
|No
|}
Meaning of Block 2 Bits
* GTYPE: Group Type 
* B0: If B0=0 then Message Group Type A else Type B
* TP: Traffic Program. Indicates this channel includes periodic [[traffic report]]s.
* PTY: Program Type (See {{section link||Program types}}.)
* ????: Rest of the bits are group type dependent

===== Message version A =====
{| class="wikitable"
|-
|
|Block 1
| colspan="5" |Block 2
|Block 3
|Block 4
|-
|Block Meaning
|Program Identification Code
|Group Type
|B0
|TP
|PTY
|APP
|Group Specific Payload
|Group Specific Payload
|-
|Block Payload Bit Value
|XXXX XXXX XXXX XXXX
|XXXX
|0
|X
|XXXXX
|XXXXX
|XXXX XXXX XXXX XXXX
|XXXX XXXX XXXX XXXX
|-
|Offset Value (Sync)
|Offset A
| colspan="5" |Offset B
|Offset C
|Offset D
|}

===== Message version B =====
Block 3 is used for repeating program identification code.
{| class="wikitable"
|-
|
|Block 1
| colspan="5" |Block 2
|Block 3
|Block 4
|-
|Block Meaning
|Program Identification Code
|Group Type
|B0
|TP
|PTY
|APP
|Program Identification Code
|Group Specific Payload
|-
|Payload Bit Value
|XXXX XXXX XXXX XXXX
|XXXX
|1
|X
|XXXXX
|XXXXX
|XXXX XXXX XXXX XXXX
|XXXX XXXX XXXX XXXX
|-
|Offset Value (Sync)
|Offset A
| colspan="5" |Offset B
|Offset C'
|Offset D
|}