> For the complete documentation index, see [llms.txt](https://docs.sealsecurity.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sealsecurity.io/reference/naming-and-versioning/sp-model.md).

# The -sp\[N] model

A sealed version's identity is the origin version's identity plus an iteration suffix. The canonical form is `sp` followed by a positive integer. The exact placement and separator vary by ecosystem (see [Per-ecosystem nuances](/reference/naming-and-versioning/per-ecosystem.md)).

For `ejs@2.7.4`, the first sealed iteration is `2.7.4-sp1`, the second is `2.7.4-sp2`, and so on. Both substitute for `2.7.4` in any context that accepts `2.7.4`; what differs is the set of vulnerabilities each one closes.

## Why N increments

The iteration number grows whenever Seal produces a new sealed version of the same origin version. Reasons:

* A new vulnerability is disclosed against the previously latest sealed iteration. Seal builds a new iteration that closes the new vulnerability in addition to the ones the earlier iterations closed.
* Coverage is expanded. Seal extends a sealed iteration to cover an additional vulnerability that was either out of scope or not yet known when the previous iteration was published.

Each iteration is cumulative: `-sp2` closes everything `-sp1` closed plus whatever drove the new iteration; `-sp3` closes everything `-sp2` closed plus more, and so on.

## Private versions

In rare cases, a vulnerability cannot be fully patched without affecting some edge cases. These cases are uncommon overall, but customers with a broad open-source footprint encounter them from time to time. Seal does not release these versions on the platform automatically, because customers need to be informed about potential side effects and should thoroughly test the updated version.

Seal manually enables the use of private versions to ensure customers are aware of possible implications. Private versions are identifiable by a `p[N]` suffix on top of the sealed version. For example, if the public version is `ejs@2.7.4-sp2`, the private version would be `ejs@2.7.4-sp2p1`, `ejs@2.7.4-sp2p2`, and so on.

See [Private versions](/discovering/private-versions.md) for the chapter that covers the workflow.

## Related

* [Per-ecosystem nuances](/reference/naming-and-versioning/per-ecosystem.md)
* [Renamed packages](/reference/naming-and-versioning/renamed-packages.md)
* [Private versions](/discovering/private-versions.md)