A system identifier is used to form the name of system objects in the IBM® i operating system. There are two types of system identifiers: ordinary identifiers and delimited identifiers.
For example, “PRIVILEGES” is in uppercase and the characters within the delimiters form an ordinary identifier; therefore, it has a length of 10 bytes and is a valid system name for a column. Alternatively, “privileges” is in lowercase, has a length of 12 bytes, and is not a valid system name for a column because the bytes required for the delimiters must be included in the length of the identifier.
WKLYSAL WKLY_SAL "WKLY_SAL" "UNION" "wkly_sal"
See Naming conventions for information on the maximum length of identifiers.