8.	Recommendation I.140 (old Recommendation I.130 - Red Book)

ATTRIBUTE TECHNIQUE FOR THE CHARACTERIZATION OF TELECOMMUNICATION SERVICES	SUPPORTED BY AN ISDN AND NETWORK CAPABILITIES OF AN ISDN

1.	General considerations

The purpose of this Recommendation is to introduce the attribute technique and to describe attributes and list attribute values. Attributes are used in the characterization of services and network capabilities provided by

an ISDN. The attribute technique can also be used to describe the salient features of other objects of study in telecommunications, e.g., charging.

This Recommendation (in the general I.100 Series) will act as a library of all attributes and attribute values used in other I-Series Recommendations. The inclusion of a particular attribute value in this Recommendation does not mean that this particular object is being recommended by CCITT, but that it is a potential attribute (or attribute value) which may be used in a particular Recommendation in the I-Series (e.g., to describe a CCITT Recommended service).

Annex 1 includes all attributes and their values so far identified and defined.

2.	Attribute technique

2.1	Outline of the technique

This technique is used to describe objects in a structured, simple manner and to highlight the important aspects of the object. In order to be able to identify comparable objects, e.g., Bearer Services, the general concept of the object is broken down in a number of salient features. The salient features are termed Attributes. Each attribute is independent of the others so that a change in the value of one will not affect the others. To describe a particular object the attributes are assigned values which identify that object.

It is not always necessary or useful to describe an object in great detail and so attributes have been graded into three levels:

-	dominant attributes, these define a sub-set containing similar objects, this sub-set is termed a class or category;

-	secondary attributes, these define a particular object; and

-	qualifying attributes, these define variants of an object.

Characterization of attributes should be used in the I-Series of Recommendations when appropriate.

2.2	Basic rules

-	Each attribute is assigned a name and definition.

-	Some attributes may apply to only one object, others may be applicable to several objects. In this case the same attribute name is used.

-	A given value should have the same name and definition in all Recommendations.

-	Depending on the nature of the object described, a particular attribute may need to be used more than once.

-	Each attribute should be described by three perspectives; generic, service and network.