Importing and Exporting Identifiers

Identifiers from the used or required module are not, by default, exported into the caller's namespace.

Subroutines and other variables must be accessed using fully qualified names, e.g.:
my $return = &Package_name::sub_name($param1, $param2);
Some modules export certain identifiers into the calling package.
- Most inherit their import functionality from Exporter.pm and store the names of the variables to be exported in an array @EXPORT.
Some modules allow users to request particular identifiers to be exported into their namespace.
- The names of these vars are stored in the array @EXPORT_OK .
- The caller must request these vars when the module is used:
  use Employee::PartTime ('wages', 'show_record');
The preferred default:
- Export nothing
- Make user-accessible functions available in @EXPORT_OK
- Why?
However, the author of the module can do as he or she pleases.