612   AccessResult for value(s) - MMS encoding not entirely clear.

Created: 21 Mar 2008

Status: In Force (green)

Part: Part 8-1 (2004)


Page: 55

Clause: 17.2.1

Paragraph: AccessResult for value(s)

Issue: Definition of AccessResult for data value(s) is somewhat not entirely clear. It states "This set of Access Result shall contain ..." which in MMS context may imply that it should be a SET (or SEQUENCE) of data.
This can be misleading, especially in combination with errorneus report MMS encoding example in IEC61850-7-1 Fig. 61 (see Tissue 611).

Proposal: Rephrase 1st sentence of "AccessResult for data value(s)" in a same manner as it is presently "AccessResult for ReasonCode(s)" so it will state:
"The values shall be encoded as multiple AccessResults. Each AccessResult shall contain MMS data corresponding to the DatSet that are being reported."

Discussion Created Status
11 Dec 08 In Force (green)
The issue is that the DataSet may contain a single or multiple members. It is clear in ISO 9506 what this means. It is not advisable to start re-creating text/procedures from 9506 in 61850.

Note "set" is lower case and does not imply ASN.1, but rather normal English.

Will change the word "set" to "list".
26 Mar 08 Ballot Period
The point is that the current statement "This set of AccessResult ..." can be interpreted in a way that "AccessResult for data value(s)" is kind of structure (like MMS structure) instead of raw sequence of AccessResults. This would lead to encoding as in (erroneous - what coincidence) example at IEC61850-7-1, Figure. 61 (Please see tissue 611).
Regarding eventual precedent, if any then it is already present in "AccessResult for ReasonCode(s)". I am just trying to propose same/similar formulation for "AccessResult for data value(s)".
21 Mar 08 Discussion (red)

I do not believe that such a qualification is not needed as it is clear in ISO 9506 (e.g. MMS). I think it is a bad precedent to start trying to include what is in 9506 within 8-1.
21 Mar 08 Discussion (red)
My proposed rephrase formulation is not entirely clear either. It should state:
"The values shall be encoded as multiple AccessResults. AccessResults shall contain MMS data corresponding to the DatSet members that are being reported."
21 Mar 08 Triage


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