Parts 23-27: Titles not confirmed
| Document number | OPC 10000-23 and above |
|---|---|
| IEC designation | IEC 62541-23 and above |
| Colloquially | Parts 23-27 |
| Group | Core |
The core part numbering continues past 22, and we have not confirmed the titles of Parts 23 to 27. Rather than guess at them, this page exists to record the gap honestly. Confirm the titles against the publisher's own current reference documentation before citing any of them.
What we know and what we do not
We know the numbering does not stop at the block that is well established through the low twenties. We do not know the titles of Parts 23 through 27, and we could not check them against a current source. A part number with a guessed title is the single most quotable kind of wrong fact - it gets copied into specifications, syllabuses and tender documents, where it costs somebody a phone call at best and a procurement error at worst. So we are not publishing a guess, and this is deliberately the thinnest page on this site.
What to do instead
If a document, a vendor datasheet or a colleague has cited a part in this range, get the title from the publisher's own current reference documentation and take the number from there. If you are the one writing a requirement, specify what you need in terms that can be tested on a running server: a namespace URI with a version, a profile or facet the server claims in its ServerProfileArray, or a named conformance unit. All three are checkable on the equipment in front of you, and none of them depends on a part number being right.
What it defines
| Concept | What it is |
|---|---|
| What is established | The core series continues past 22. The numbering scheme itself is unchanged: OPC 10000-N, IEC 62541-N and Part N remain three names for one document. |
| What is missing | The titles of Parts 23, 24, 25, 26 and 27. We have no confirmed title for any of them and are not offering a best guess. |
| Why there is no guess here | A part number paired with a plausible title reads as authoritative and travels into documents that matter. A page that says we do not know cannot mislead anyone. |
| How to resolve it | Take the number and the title together from the publisher's own current reference documentation, and cite the edition you read. |
| What to specify instead | A namespace URI plus a version, a claimed profile or facet, or a named conformance unit. All are verifiable against a running server; a part number is not. |
| What a server can tell you | NamespaceArray gives you every model a server loads, NamespaceMetadata gives their versions, and the capability codes and ServerProfileArray give you what it claims to implement - none of which requires knowing a part number. |
Do you need to read it?
Anyone who has seen a part number in this range cited somewhere and wants to know what it is. The honest answer is that we do not know yet, and the useful answer is that a namespace URI and a version will get you further than a part number in almost every practical situation.
Traps that trace back to this part
- Do not cite a part in this range from a secondary source, this page included. Confirm the number and the title together against the publisher's own current reference documentation, because a number that is right with a title that is wrong is still a wrong citation.
- A requirement written against a part number cannot be tested on a server. A requirement written against a namespace URI, a version, a profile or a conformance unit can be, and that is what an acceptance test needs regardless of what the part is called.
Last verified 7 September 2026 against OPC UA 1.05.07. The specification parts themselves are published by the OPC Foundation. OPC UA Connect is an educational resource and is not affiliated with the OPC Foundation.