JP Dakota (5/3/2011)
According to Pierre Dorion at TechTarget.com - The RTO, as its full name implies, is a goal or an ideal time in which you need a specific function or service to be available following an interruption. In essence, the RTO represents the maximum amount of time before an organization is negatively impacted by the interruption of one its core business processes or functions.In that case I would argue that an organization is negatively impacted when they can't log in.
I hope I pasted the quote here properly. Don't want to use info improperly.
I don't know that Tech Target is more authoritative than any other source, but RTO can be defined differently in different situations. The important thing is that you develop this into your SLA and are aware of how your customers/management view the RTO requirements in a DR situation.