3 The map of the groups, and where the weight sat

3.1 Nobody owns this subject

79 separate meetings have had a sensing document on the table ^[1]. That is the first thing to understand about the area: there is no one group to ask and no one document to read.

3GPP splits a subject by rung rather than by topic. Stage 1 is what the system must do, stage 2 is how it is put together, stage 3 is the bytes on the wire, and the radio is its own world again. Each rung has its own group, its own meeting series and its own document numbering.

So a subject like sensing arrives at each group in turn, and the record shows it doing exactly that.

3.2 Who did what

The counts below are documents carrying one of the fourteen sensing acronyms, filed at that group's own meetings.

Group	What it did here	Documents	Meetings on the record
SA1 SA1	asked what the system must do	640	SA1#98-e to SA1#109
SA2 SA2	the architecture side	995	10 meetings, SA2#167 to SA2#175
RAN1 RAN1	the radio side	872	16 meetings, RAN1#116 to RAN1#126
SA6 SA6	the application layer	284	SA6#68 to SA6#73
RAN3 RAN3	the interfaces, and now the radio rule-writing	259	RAN3#129-bis to RAN3#133
SA3 SA3	security and privacy	227	SA3#124 to SA3#128
SA5 SA5	charging and management	127	three meetings, SA5#165 to SA5#167
CT4 CT4	the protocol detail	9	CT4#135
RAN2 RAN2	one liaison, no work of its own	1	RAN2#133
RAN plenary RAN	where the radio studies and work items were opened	53	—
SA plenary SA	where the system studies and work items were opened	25	—

A liaison is a letter from one group to another, or to a standards body outside 3GPP. A plenary is the meeting above the working groups, where work is opened and finished work is signed off.

Two ways of reading "biggest" disagree here, and both are worth having. SA2 has filed the most documents. RAN1 has spent the most meetings on it — sixteen, more than any other group. And the single busiest meeting belongs to neither: SA1#101 handled 154 sensing documents, more than any other meeting on the record ^[3].

3.3 The acronyms to search for

Every document filed under this area carries a work item acronym. Searching by acronym is the only reliable way to find them, for a reason the last chapter of this course goes into.

Acronym	Whose it is	Documents
FS_Sensing_NR FS_Sensing_NR	RAN1, the Rel-19 channel-model study	776
FS_Sensing_ARC FS_Sensing_ARC	SA2, the architecture study	706
FS_Sensing FS_Sensing	SA1, the original use-case study	521
FS_Sensing_NR_bis FS_Sensing_NR_bis	RAN1, the second radio study	407
Sensing-ARC Sensing-ARC	SA2, the architecture specification	302
FS_Sensing_SEC FS_Sensing_SEC	SA3, security and privacy	227
FS_Sensing_APP FS_Sensing_APP	SA6, the application-layer study	215
Sensing Sensing	SA1, the requirements specification	128
Sensing-APP Sensing-APP	SA6, the application-layer specification	75
FS_Sensing_CH FS_Sensing_CH	SA5, charging	67
FS_Sensing_OAM FS_Sensing_OAM	SA5, management	61
Sensing-CT Sensing-CT	CT4, the protocol detail	9
NR_Sensing_bis-Core NR_Sensing_bis-Core	RAN3, the radio specification	1

The pattern is worth learning. In this area, every study's acronym begins FS_, and the acronyms without that prefix are the rule-writing that follows a study.

3.4 The trap in counting work items

The work plan holds 18 entries ^[4] under those 14 acronyms ^[5]. The difference is not an error.

Sensing has three entries and Sensing-CT has three, one per release or per group, all pointing at the same description document Sensing Sensing Sensing-CT Sensing-CT.

The RAN work item is filed twice as well — once as the feature and once as its core part, both described by the same document. Only the core-part entry has a document against it so far NR_Sensing_bis ^[6].

Two more gaps to know about before trusting any group list. The CT work item names CT3 as doing half the job, but no document at a CT3 meeting carries one of these acronyms yet, so CT3 has no entry and no count ^[7]. And the oldest work item, the SA1 study, has a work plan entry and an approval document but no work item description on this machine — so no objective and no leadership line is recorded for it FS_Sensing.

3.5 Where to read this yourself

The shortest statement of what any group promised is its work item description. Four of them cover the rule-writing now under way: RP-261566 for the radio, SP-260297 for the architecture, SP-260317 for the application layer and CP-261274 for the protocols RP-261566 SP-260297 SP-260317 CP-261274.

This school does not carry the text of those documents, or of the specifications they name. It tells you which number to fetch.