Abstract: A data storage medium stores string data that can be used in character recognition and instructions for accessing the string data. The string data includes data units that can be accessed by a processor in executing the instructions. The processor can use character data indicating characters of a string to access a sequence of the data units that ends with an ending subsequence. The ending subsequence includes acceptance information indicating whether a string whose sequence of data units ends with the ending subsequence is an acceptable string. If so, the ending subsequence also includes category set information indicating a set of categories for strings whose sequences end with the ending subsequence. The categories can include words, numbers, compound words, and so forth. The acceptance information can include a bit in a character label data unit that includes information indicating the character type of an ending character.