Projected Service Outage
Projected Service Outage (PSO) is a document that is produced and distributed under the auspices of the Change Management process of ITIL version 3.
The PSO is linked heavily to the Change Schedule (CS) that details the upcoming changes to the IT infrastructure that have been approved. The PSO is a reflection of the fact that changes to the infrastructure can lead to temporary or permanent changes in the availability of an IT Service.
Projected Service Outage therefore can be a document of negotiation that is used to make changes to Service Level Agreements (SLAs). Like SLAs the PSO is produced for the benefit of customers and other stakeholders.
The PSO can also be used to document changes in availability due to scheduled maintenance. It is perhaps easier to think of the PSO as a register, that can be later referred to as a summary of changes and outages that may help to explain differing levels of agreed availability.