2010   Ellipsis usage clarification

Created: 03 Dec 2025

Status: Discussion (red)

Part: Part 9-2 (2020; Edition 2.1)

Links:

Page: 20

Clause: 8.5.2

Paragraph: Table 14

Issue

The Table 14 is using ellipsis to show possible extension. This is used in certification test cases to handle future extensions of SMV, tested in sSvs4 test case.

This definition is based on ASN.1 specification, more preciselly section 3.8.35.

But the relationship between elipsis in table 14 and ASN.1 definition is not clear.

Proposal

Please add text with Table 14 to detail this possibility of extending SMV following ASN.1 ellipsis definition

Discussion Created Status
Moved to discussion. I suggest to treat this tissue as editorial. 04 Jun 26 Discussion (red)
I agree, this point would need a clarification in the next revision. 27 May 26 Accepted
Propose to accept this tissue. 26 May 26 Triage
From Ben Day, SEL:

I would like to share my perspective with you on Tissue #2010, Ellipsis usage clarification. Since the tissue is in the triage state, I do not have permissions to comment directly via the Tissue DB.



I agree that Table 14 needs clarification, especially with respect to compatibility between editions.



It is important to understand that IEC 61850-9-2 2004 did not permit extension of the ASDU. The only ellipsis in the first edition corresponds to the “IEC 61850-9-2 Specific Protocol ::= CHOICE” and meant that the 9-2 message could encode from a choice of a 9-1-Pdu, savPdu, or some future extension. The ASDU is defined as a SEQUENCE of items starting with MsvID and ending with the Samples. Because the ASDU SEQUENCE does not include an ellipsis, it is inextensible.



Likewise, IEC 61850-9-2 2011 did not permit extension of the ASDU. Again, the only ellipsis in the second edition corresponds to the “IEC 61850-9-2 Specific Protocol ::= CHOICE”. The ASDU was again defined as a SEQUENCE that does not include an ellipsis, making it inextensible. But the second edition added a SmpMod as an OPTIONAL item in the SEQUENCE, making it incompatible with the first edition if SmpMod is present.



IEC 61850-9-2 2011 AMD 1 extends the ASDU SEQUENCE by adding SynchSrcID as an OPTIONAL item in the SEQUENCE, making it incompatible with the second edition if SynchSrcID is present. Fortunately, AMD 1 did add an ellipsis to the ASDU. As such, future editions may add additional items to the ASDU SEQUENCE and AMD 1 implementation must support such extensions.



I agree that any clarification is editorial since the ASN.1 is definitive, but it is interleaved in and around a table which leads to some confusion. And, it should be clear that only the latest edition can offer forward compatibility with respect to additions to the ASDU SEQUENCE. 		26 May 26 Triage
Table 14 is defining an ASN.1 message specifcation. It is using ANS.1 syntaxt, including the elipsis to force the subscriber for some forward compatibility.
Elipsis are an essential part to allow the standard to move on with extended defintion without breaking compatilibity with existing implementation.
This tissue could be treated as an editorial one, because from the technical aspect, elipsis are clearly defines in the ASN.1 stadard.
07 Jan 26 Triage

 

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