Ptolemy had numbered these at 1,022, grouped into 48 constellations. Each creation is numbered and signed. Subtitles are numbered sequentially, starting at 1. These units are now numbered ES-0 through ES-5. They are numbered from 800, and are limited to . Inodes are numbered sequentially, starting at 0. When first published, the books were not numbered. They were numbered 1 to 8 in 1972. Above ground floors are numbered 1 to 5. Airways are numbered and standardized on charts. They are typically numbered from 0 to 21. Elections are held in the spring of even numbered years. The ID card has been uniformly numbered since 1965. These have been numbered 326 to 334. The shafts are numbered 1 to 4, south to north.