Using national group items in SQL statements
You can use a national group item as a host
variable in an EXEC SQL statement. The national group
item is treated with group semantics (that is, as shorthand for the
set of host variables that are subordinate to the group item) rather
than as an elementary item.
About this task
Because
all subordinate items in a national group must have USAGE
NATIONAL, a national group item cannot describe a variable-length
string.