Wednesday, May 22, 2013

What does the OSI-AP-Title “1,3,9999” mean?

Is this identifier more than just a number defined by somebody from IEC TC 57 WG 10? No! The underlying definition is the “OSI Object Identifier model” (OID). This numbering schema has been defined some 30 years ago in the context of ASN.1.

MMS and MAP 3.0 used this identifier concept to get unique object identification (see MAP 3.0). The basics of MMS and OSI have been defined in the 80’s … and a lot of people are still (and again and again) struggling with these concepts that have no real use these days. The concept of OIDs is great – just we do not make use of it in the domain of IEC 61850.

Many people I have trained and many other people have no clue what these numbers mean and what purpose they serve.

“In computing, an object identifier or OID is an identifier used to name an object (compare URN). Structurally, an OID consists of a node in a hierarchically-assigned namespace, formally defined using the ITU-T's ASN.1 standard, X.690. Successive numbers of the nodes, starting at the root of the tree, identify each node in the tree. Designers set up new nodes by registering them under the node's registration authority. The root of the tree contains the following three arcs:
0: ITU-T
1: ISO
2: joint-iso-itu-t”


The OID is used by ACSE to establish an application association … for MMS.

Definition in IEC 61850-8-1 Edition2:


Example in SCL notation:


Here is the meaning of the values “1”, “3”, and “9999” for the OSI-API-Title according to

“1” –>


“3” –>


“9999” –>


The value is a reserved value ->


IEC 61850 and especially IEC 61850-8-1 does not (yet?) use the registration of further identifier for specific application.

So, applications (servers) need to use the “1,3,9999.13” to allow MMS/ACSE to establish an application association! Please make sure that your client uses the correct setting of this and the other configuration attributes in the address.

The last value “13” is not known to me … could not find any hint on that. It is not registered.

Please do not change this OID “1,3,9999” used by MMS. The value “1,3,9999.13” is used as an example in 8-1 Ed2. The “13” may be replaced or omitted – I guess.

The value could be empty as well. The following attributes are all optional (IEC 61850-8-1 Ed2):


These are mandatory:

image image

Some vendors fix the values ion their PIXIT documents:

Example 1 (Alstom Mx70):


Example 2 (ABB COM600):


Example 3 (Siprotec):


Please check the documentation of the vendors’ IEDs to figure out how the various attributes are used and which ones are required!

Good luck!

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