Methodology
Classification labels
Where a service or a group is documented operating again after an action, that later activity is recorded as its own row against the original entry. Two vocabularies describe it: what the successor's relationship to the original is, and how strongly the sources support that reading. Both are defined in the dataset. Silence is not read as a shutdown, and a reused name is not read as a return.
| Relationship | Definition |
|---|---|
| Same operators | The same people are documented running the replacement. |
| Same service on replacement infrastructure | The service itself came back on different domains or servers. Whether the same people run it is not established. |
| Rebrand | The service returned under a different name, with continuity documented. |
| Partial operator continuity | Some of the original operators appear in the successor, not all of them. |
| Copycat | Someone else took the name or the model. No continuity of people or infrastructure is documented. |
| Ecosystem successor | A different service absorbed the users or the market. No direct continuity with the original. |
| Claimed return | A return was announced, by the operators or by a party claiming to be them, and nothing independent confirms it. |
| Relationship not established | A successor was recorded but its relationship to the original is not established. |
| Confidence | Definition |
|---|---|
| Confirmed | An official source states the link. |
| High | Well supported by the cited sources, without an official statement of the link. |
| Medium | Supported by the cited sources but not settled. |
| Low | Weakly supported. Recorded so the possibility is visible, not because it is established. |
| Disputed | The cited sources disagree about whether the link is real. |
| Not established | Not graded. |
On the return class letters
Some records also carry a return class, a single letter from A to G. That grading comes from the source dataset and its scale is published nowhere in the data, so this site does not translate the letters into words. Where a letter appears it is shown as it is, labeled "Return class B" and nothing more.
To judge whether something came back, read the relationship and the confidence above, the date the successor was first seen, and whether it was seized again in a later action. Those fields are defined. The letter is not, and inventing a definition for it would be the same kind of guess this index exists to avoid.