The Service Catalogue provides the ability to contain critical information in a central repository accessible by both the IT department and the Business.
The information contained within the Service Catalogue relates to all Services provided by the IT department to the Business. The Service Catalogue is generic and can be applied across all platforms, environments or geographical locations of any organization.
ITIL only provides minim definition for a Service within the Service Catalogue. We'd suggest that the following make a good place to start:
Service Description: The Service Description should be written in easy to understand, simple, non technical terms that almost any person within the organization could understand.
Service Owner: The Service Owner is the person within the organization is responsible for the Service although this may not include the actual delivery.
Criticality: The criticality of the Service is determined by the Business.
Relationships: A Service is linked to the actual items within the I.T infrastructure that deliver it. This enables analysis across the chain to determine impacts of outages, upgrades etc.