New entrant status can be used when an airline holds less than 5 slots at an airport on a day of the week during a season (the slots must be part of a series).
A level 2 airport is a Slot Facilitated Airport; where demand is close is capacity and coordination is need to ensure the demand does not above the capacity. Airlines that operate into level 2 airport, do not accrue historic precedence.
A level 3 airport is a Fully Coordinated Airport; where demand exceeds the capacity and due to the high volume of demand, there is no opportunity to re-schedule flights on a voluntary basis.
When the demand of slot requests exceeds the capacity of the airport infrastructure.
A slot is not route specific (excluding local rules), but it is equipment and time specific.
According to the IATA World Slot Guidelines, a slot is a permission to operate an aircraft movement at a scheduled time of arrival or departure on a specific date and time at an airport.