Abatement | A deduction from the service charge that LUL pays to an Infraco due to performance worse than that agreed in the contract.
Ambience | A performance measure covering the quality of the environment for passengers, including the cleanliness and general condition of trains and stations.
Arbiter | An independent authority appointed by the Secretary of State for Transport to resolve disputes between the parties on the financial terms of the PPPs and the costs to be recovered under them - at Periodic Review, but possibly other times.
Availability | A measure of passengers' total additional journey time resulting from train service or station disruption (see also Lost Customer Hours).
BCV | Bakerloo, Central, Waterloo & City, and Victoria lines. Now the responsibility of Metronet.
Capability | A performance indicator that measures the infrastructure's ability to support train services. It is based on average journey time per passenger, for a given time of day, and for a given line or part of a line and includes Journey Time Capability, Service Consistency and Service Control.
Comfort Letter | A letter of awareness issued by the Secretary of State to senior lenders to each of the three PPPs. The comfort letter sets out the amounts of debt and indicates that he would consider re-setting the transport grant in various circumstances where London Underground cannot meet its obligations. The comfort letter also recognises the possibility of the transport grant being insufficient to meet the potential sums due on termination and that he would not "stand by and do nothing in those circumstances".
Corrective action notices | Notices that LUL gives to the Infracos in the event of continued poor performance, specifying times to remedy contract performance.
Fault attribution | All incidents go through the fault attribution process, which are inputted on-line with a specially designed computer system and which attributes responsibility to LUL or an Infraco on the basis of pre-determined rules.
Fault rectification | The speed and quality of fixing faults with for example Help Points, Dot Matrix Indicators and CCTV.
Greater London Authority (GLA) Act 1999 | The act that established a Mayor for London, with associated powers over affairs such as transport and policing.
Grey assets | Assets that are in unclassified condition at the start of the PPPs, and which the Infracos must classify by the first periodic review in 2010.
Health and Safety Executive | The statutory body established by the Health and Safety at Work etc. Act 1974, responsible for accepting and enforcing London Underground's railway safety case (the document which describes how LUL manages safety).
Infrastructure companies (Infracos) | The three organisations (Infraco BCV, Infraco JNP and Infraco SSL) responsible for delivering infrastructure services to London Underground under the PPP contracts.
Infrastructure | Railway, trains, stations and depots on London Underground's network (including track, signals, tunnels, bridges, embankments, platforms, escalators, lifts).
Infrastructure service charge (ISC) | The amount payable under the PPP contract by London Underground to the Infraco, adjusted periodically as set out in the Service Contract, as agreed between the parties, or determined by the Arbiter at Periodic Review. The ISC covers the Infraco's costs of maintaining, renewing and upgrading the infrastructure, including overheads, profit and financing costs.
JNP | Jubilee, Northern and Piccadilly lines. Now the responsibility of Tube Lines.
London Regional Transport | A nationalised industry previously responsible for London Underground and answerable to the Department for Transport.
London Underground | (previously a subsidiary of London Regional Transport, now part of Transport for London) - Body responsible for operating passenger trains and stations and for passenger safety.
Lost Customer Hours (LCH) | The amount of customers, "lost" time due to severe disruption, calculated using a weighted formula to reflect the number of passengers likely to be travelling on the affected part of the network when the delay occurs.
Major Enhancements | Changes to the scope of the contract and of negotiable value, where design, feasibility, etc. are required and which the Infraco is not mandated to deliver.
Metronet | A joint venture comprising Atkins, Balfour Beatty, Bombardier Transportation, EDF Energy (formerly SEEBOARD) and Thames Water, with responsibility for Infraco BCV and Infraco SSL.
Partnership Director | A non-executive director, appointed by London Underground, who sits on the board of all the Infracos and has a mandate that includes ensuring good communication and co-operation between the parties.
PFI | Private Finance Initiative. A policy introduced by the Government in 1992 to harness private sector management and expertise in the delivery of public services, while reducing the impact of public borrowing.
PPP | Public Private Partnership. In this case, the partnership between the public sector London Underground and three private sector infrastructure companies under the 30-year PPP contracts.
Rolling stock | Trains, cabs, coaches, locomotives, self-propelled mechanical plant and other vehicles which can operate alone or together on the track, together with all powered and unpowered Track trolleys.
Periodic review | A provision in the PPP contract which, every 7½ years, allows London Underground's payments to the Infracos to be reset to take account of changed circumstances and cost increases that an "economic and efficient" Infraco would incur.
Safety Case | The statutory safety case prepared by LUL as a train operator that sets out how LUL will manage passenger safety. The Safety Case must be accepted by the Health and Safety Executive in compliance with the Railways (Safety Case) Regulations 2000.
Service points | Service Points are allocated to the Infracos for failures to meet certain requirements of the performance specification. The level of abatement is £50 per Service Point. Service Points are used to incentivise Infracos to fix reported faults.
Shadow running | A three year period preceeding the closure of the PPP deals during which the PPP framework was trialled and modified.
Specified right | LUL specified rights' are defined in the PPP contracts and cover a number of projects that were not included, because they were insufficiently defined or there was uncertainty about whether LU would wish to proceed with them.
Step-in rights | If the Infraco fails to comply with a Corrective Action Notice, LUL can take steps itself to remedy the problem, or ask another Infraco or a third party to do so. LUL also has emergency step-in rights.
SSL | Circle, District, Metropolitan, East London and Hammersmith & City lines. These lines are only just below ground level, having been built in 'cut and cover' tunnels, and are now the responsibility of Metronet.
Transport for London (TFL) | The body created under the Greater London Authority Act 1999, which took over responsibility for London Underground operations from July 2003.
Tube Lines | A joint venture comprising Amey, Bechtel and Jarvis, with responsibility for Infraco JNP.