the creation of oasis nodes allowed for energy to be scheduled across multiple power systems, creating complex strings of single "point-to-point" transactions which could be connected end-to-end to literally travel across the continent. this frequently created situations where it was difficult or impossible for transmission system operators to ascertain all of the transactions impacting their local system or take any corrective actions to alleviate situations which could put the power grid at risk of damage or collapse. the nerc tag was implemented as a result of this new problem introduced by deregulation.