178   Inconsistency in ASN encoding between 9-1 and 9-2

Created: 21 Jul 2005

Status: In Force (green)

Part: Part 9-2 (2004)

Links:

Page: 14

Clause: 7.3.1

Paragraph: 4

Category: Issue for edition 2 of this part

Issue

9-1 (Clause 7.3.1) states that the top-level ASN decoding for SV
APDUs is:

IecSavPdu ::= CHOICE {
9-1-Pdu [0] IMPLICIT OCTET STRING, -- Used for 9-1 APDU
savPdu [1] IMPLICIT SavPdu, -- Reserved for 9-2 APDUs

while 9-2 (Clause 8.5, Table 13) defines the same as:

IEC 61850-9-2 Specific Protocol ::= CHOICE {
9-1-Pdu [0] IMPLICIT OCTET STRING, -- Reserved for 9-1 APDU
savPdu [APPLICATION 0] IMPLICIT SavPdu,

[1] and [APPLICATION 0] will not result in the same binary BER
representation.

Proposal

Harmonize 9-1 and 9-2.

Based on 9-1 comments in Clause 7.3.1 (value of the tag equal to 0x80
for 9-1) and examples in 9-2, Annex A.3 (value of the tag equal to
0x60 for 9-2), it seems that the definition given in 9-2 satisfies
both.