22. An apparatus for recognizing an identifier entered by a user, the entered identifier including a first plurality of predetermined characters, wherein the characters are selected from a first set of characters, the first set of characters including a first total number of characters, the system comprising: means for receiving a recognized identifier based on the entered identifier, the recognized identifier comprising a second plurality of predetermined characters; a first memory that stores a plurality of reference identifiers, each one of the reference identifiers comprising a different plurality of predetermined characters, each one of the different plurality of predetermined characters belonging to the first set of characters; a second memory that stores a first arrangement of character recognition probabilities, the first arrangement of character recognition probabilities encompassing a second set of characters having a second total number of characters and is a superset of the characters of the first set of characters, each of the character recognition probabilities representing a probability that a certain recognized character corresponds to a certain entered character; and a third memory that stores constraint data; and a processor, in communication with the means for receiving, the first memory, the second memory, and the third memory, that produces in accordance with the constraint data of the third memory a constrained arrangement of character recognition probabilities, the constrained arrangement of character recognition probabilities being produced by constraining the first arrangement of character recognition probabilities to encompass a third set of characters constituting a subset of the second set of characters, the processor determining for every one of the plurality of reference identifiers a corresponding identifier recognition probability, each of the corresponding identifier recognition probabilities being determined on the basis of the constrained arrangement of character recognition probabilities, the processor selecting the reference identifier most likely matching the entered identifier based on the identifier recognition probabilities.
22. An apparatus for recognizing an identifier entered by a user, the entered identifier including a first plurality of predetermined characters, wherein the characters are selected from a first set of characters, the first set of characters including a first total number of characters, the system comprising: means for receiving a recognized identifier based on the entered identifier, the recognized identifier comprising a second plurality of predetermined characters; a first memory that stores a plurality of reference identifiers, each one of the reference identifiers comprising a different plurality of predetermined characters, each one of the different plurality of predetermined characters belonging to the first set of characters; a second memory that stores a first arrangement of character recognition probabilities, the first arrangement of character recognition probabilities encompassing a second set of characters having a second total number of characters and is a superset of the characters of the first set of characters, each of the character recognition probabilities representing a probability that a certain recognized character corresponds to a certain entered character; and a third memory that stores constraint data; and a processor, in communication with the means for receiving, the first memory, the second memory, and the third memory, that produces in accordance with the constraint data of the third memory a constrained arrangement of character recognition probabilities, the constrained arrangement of character recognition probabilities being produced by constraining the first arrangement of character recognition probabilities to encompass a third set of characters constituting a subset of the second set of characters, the processor determining for every one of the plurality of reference identifiers a corresponding identifier recognition probability, each of the corresponding identifier recognition probabilities being determined on the basis of the constrained arrangement of character recognition probabilities, the processor selecting the reference identifier most likely matching the entered identifier based on the identifier recognition probabilities. 25. The apparatus according to claim 22, wherein each one of the entered identifier, the recognized identifier, and the plurality of reference identifiers comprises a plurality of numbers.