4791cd8c_mentation__7_2__Binary_Strings__BYTEA
[SQL99] A binary string literal is comprised of an even number of hexadecimal digits, in single quotes, preceded by "X", e.g. X'1a43fe' [BYTEA] 
A binary string literal is comprised of octets escaped according to the rules shown in Table 3-7
PostgreSQL: Documentation: 7.2: Binary Strings