Social (or socio-) cost-benefit analysis

1) A system used in decision making, in particular for determining whether a particular project should go ahead, by comparing different projects, by comparing present and future time periods and by taking the viewpoint of society rather than that of the individual or companies.

SO₂

1) Sulphur dioxide. A constituent of vehicle exhaust emissions.

SMP

1) Statutory maternity pay. Payment made to employee following childbirth.

Smoke emission

1) It is an offence to allow a vehicle to emit smoke, also visible vapour, grit, sparks, ashes, cinders or oily substances. Smoke emissions are checked at goods vehicle testing stations and sometimes in roadside tests with smoke meters or visually by examiners.

SME

1) Small and medium-sized enterprise. Small and medium-sized firms have been identified by government as being in need of its initiative (ie UK online for business) to get online.

Smart card

1) Plastic card containing magnetic information (or incorporating a micro-chip) as with credit cards and capable of accepting and storing data. To be used with new-style digital tachographs from 2003 for electronically recording driving time and driver's working activities, etc.