The byte-manipulation functions use objects called byte specifiers to designate the size and position of a specific byte within an integer. The representation of a byte specifier is implementation-dependent; it might or might not be a number. The function byte will construct a byte specifier, which various other byte-manipulation functions will accept.
Figure 12–6 shows defined names relating to manipulating bytes of numbers.
| byte | deposit-field | ldb-test |
| byte-position | dpb | mask-field |
| byte-size | ldb |