http://en.wikipedia.org/wiki/Schengen_Area

It is granted in the following categories:[45]


Category A refers to an airport transit visa. It is required for some few nationals for passing through the international transit area of airports during a stop-over or transfer between two sections of an international flight. The requirement to have this visa is an exception to the general right to transit without a visa through an international transit area of an airport.

Category B refers to a transit visa. It is required by nationals who are not visa-free for travelling from one non-Schengen state to another non-Schengen state, in order to pass through the Schengen area. Each transit may not exceed five days.

Category C refers to a short-term stay visa. They are issued for reasons other than to immigrate. They entitle holders to carry out a continuous visit or several visits whose duration does not exceed three months in any half-year from the date of first entry.

Category D refers to national visa. They are issued by a Schengen state in accordance with its national legislation as with respect to the conditions (however, a uniform sticker is used). Only after the holder has obtained a residence title after arrival in the destination country (or a different visa), he may again travel to other Schengen countries.

Category D+C visas combine the functions of the visa of both categories: They are intended to allow the holder to enter the issuing Schengen state for long-term stay in that state, but also to travel in the Schengen area like a holder of a Category C visa.