An accession number may include the year acquired, sometimes the full date (as at the British Museum), and a sequential number separated by a period.[1] In addition, departments or art classifications within the collection or museum may reserve sections of numbers. For example, objects identified by the numbers 11.000 through 11.999 may indicate objects obtained by the museum in 1911; the first 300 numbers might be used to indicate American art, while the next fifty (11.301–350) might be used for African art. In some cases, they also include letters and other punctuation, such as commas, hyphens or slashes.[4]