DateTime::Format::Oracle may be used to convert Oracle date and timestamp values
into DateTime objects. It also can take a DateTime object and produce a date
string matching the NLS_DATE_FORMAT.

Oracle has flexible date formatting via its NLS_DATE_FORMAT session variable.
Date values will be returned from Oracle according to the current value of that
variable. Date values going into Oracle must also match the current setting of
NLS_DATE_FORMAT.

Timestamp values will match either the NLS_TIMESTAMP_FORMAT or
NLS_TIMESTAMP_TZ_FORMAT session variables.

This module keeps track of these Oracle session variable values by examining
environment variables of the same name. Each time one of Oracle's formatting
session variables is updated, the %ENV hash must also be updated.