Bit strings are strings of 1's and 0's. They can be used to
store or visualize bit masks. There are two SQL bit types:
`BIT( x)` and

`BIT` type data must match the length
`x` exactly; it is an error to
attempt to store shorter or longer bit strings. `BIT VARYING` is of variable length up to the maximum
length `x`; longer strings will be
rejected. `BIT` without length is equivalent
to `BIT(1)`, `BIT
VARYING` without length specification means unlimited
length.

Note:Prior to PostgreSQL 7.2,BITtype data was zero-padded on the right. This was changed to comply with the SQL standard. To implement zero-padded bit strings, a combination of the concatenation operator and the`substring`

function can be used.

Refer to Section 1.1.2.2 for information about the syntax of bit string constants. Bit-logical operators and string manipulation functions are available; see Chapter 4.