ITU-X225
SPDU structure: fields
SPDU global structure
| bits 8 _ _ _ _ _ _ 1 |
SPDU fields |
| 1 octet |
SI: Spdu Identifier |
| 1 or 3 octets |
LI: Length Indicator (of parameter field) |
| m octets |
Parameter field possibly including PGI and PI units |
| n octets |
User information field |
PGI unit
| bits 8 _ _ _ _ _ _ 1 |
PGI fields |
| 1 octet |
PGI: Parameter Group Identifier |
| 1 or 3 octets |
LI: Length Indicator (of parameter field) |
| m octets |
Parameters field possibly including PI units |
PI unit
| bits 8 _ _ _ _ _ _ 1 |
PI fields |
| 1 octet |
PI: Parameter Identifier |
| 1 or 3 octets |
LI: Length Indicator (of parameter field) |
| m octets |
Parameters field |
LI field
LI fields indicating lengths within the range 0-254 shall comprise one octet.
LI fields indicating lengths within the range 255-65535 shall comprise three
octets. The first octet shall be coded 11111111 (= FF H) and the second and
third octets shall contain the length of the associated parameter field with the
high order bits in the first of these two octets.
SPDU structure: list of types
| Category 0 |
Category 2 |
| GT |
Give Token |
DT |
Data Transfer |
| PT |
Please Token |
MIP |
Minor Sync Point |
|
|
MIA |
Minor Sync Ack |
| Category 1 |
MAP |
Major Sync Point |
| CN |
Connect |
MAA |
Major Sync Ack |
| AC |
Accept |
RS |
Resynchronize |
| RF |
Refuse |
RA |
Resynchronize Ack |
| FN |
Finish |
AS |
Activity Start |
| DN |
Disconnect |
AR |
Activity Resume |
| NF |
Not Finished |
AE |
Activity End |
| AB |
Abort |
AEA |
Activity End Ack |
| AA |
Abort Accept |
AD |
Activity Discard |
| GTC |
Give Token Confirm |
ADA |
Activity Discard Ack |
| GTA |
Give Token Ack |
AI |
Activity Interrupt |
| EX |
Expedited Data |
AIA |
Activity Interrupt Ack |
| PR |
Prepare |
CD |
Capability Data |
| TD |
Typed Data |
CDA |
Capability Data Ack |
| CDO |
Connect Data Overflow |
ER |
Exception Report |
| OA |
Overflow Accept |
ED |
Exception Data |
| 