+=item export
+
+Exports data. You have to have set L<exporttype> and L<format> or an error will
+occur. OBE exports are currently not implemented.
+
+=item csv_export_for_tax_accountant
+
+Generates up to four downloadable csv files containing data about sales and
+purchase invoices, and their respective payments:
+
+Example:
+ my $startdate = DateTime->new(year => 2012, month => 1, day => 1);
+ my $enddate = DateTime->new(year => 2012, month => 12, day => 31);
+ SL::DATEV->new(from => $startdate, to => $enddate)->csv_export_for_tax_accountant;
+ # {
+ # 'download_token' => '1488551625-815654-22430',
+ # 'filenames' => [
+ # 'Zahlungen Kreditorenbuchungen 2012-01-01 - 2012-12-31.csv',
+ # 'Kreditorenbuchungen 2012-01-01 - 2012-12-31.csv',
+ # 'Zahlungen Debitorenbuchungen 2012-01-01 - 2012-12-31.csv',
+ # 'Debitorenbuchungen 2012-01-01 - 2012-12-31.csv'
+ # ]
+ # };
+
+
+=item check_vcnumbers_are_valid_pk_numbers
+
+Returns 1 if all vcnumbers are suitable for the DATEV export, 0 if not.
+
+Finds the default length of charts (e.g. 4), adds 1 for the pk chart length
+(e.g. 5), and checks the database for any customers or vendors whose customer-
+or vendornumber doesn't consist of only numbers with exactly that length. E.g.
+for a chart length of four "10001" would be ok, but not "10001b" or "1000".
+
+All vcnumbers are checked, obsolete customers or vendors aren't exempt.
+
+There is also no check for the typical customer range 10000-69999 and the
+typical vendor range 70000-99999.
+
+=item check_valid_length_of_accounts
+
+Returns 1 if all currently booked accounts have only one common number length domain (e.g. 4 or 6).
+Will throw an error if more than one distinct size is detected.
+The error message gives a short hint with the value of the (at least)
+two mismatching number length domains.
+
+=back
+
+=head1 ATTRIBUTES
+
+This is a list of attributes set in either the C<new> or a method of the same name.
+
+=over 4
+
+=item dbh
+
+Set a database handle to use in the process. This allows for an export to be
+done on a transaction in progress without committing first.
+
+Note: If you don't want this code to commit, simply providing a dbh is not
+enough enymore. You'll have to wrap the call into a transaction yourself, so
+that the internal transaction does not commit.
+
+=item exporttype
+
+See L<CONSTANTS> for possible values. This MUST be set before export is called.
+
+=item format
+
+See L<CONSTANTS> for possible values. This MUST be set before export is called.
+
+=item download_token
+
+Can be set on creation to retrieve a prior export for download.
+
+=item from
+
+=item to
+
+Set boundary dates for the export. Unless a trans_id is passed these MUST be
+set for the export to work.
+
+=item trans_id
+
+To check only one gl/ar/ap transaction, pass the trans_id. The attributes
+L<from> and L<to> are currently still needed for the query to be assembled
+correctly.
+
+=item accnofrom
+
+=item accnoto
+
+Set boundary account numbers for the export. Only useful for a stammdaten export.
+
+=item locked
+
+Boolean if the transactions are locked (read-only in kivitenod) or not.
+Default value is false
+
+=back
+
+=head1 CONSTANTS
+
+=head2 Supplied to L<exporttype>
+
+=over 4
+
+=item DATEV_ET_BUCHUNGEN
+
+=item DATEV_ET_STAMM
+
+=back
+
+=head2 Supplied to L<format>.
+
+=over 4
+
+=item DATEV_FORMAT_KNE
+
+=item DATEV_FORMAT_OBE
+
+=back
+
+=head1 ERROR HANDLING
+
+This module will die in the following cases:
+
+=over 4
+
+=item *
+
+No or unrecognized exporttype or format was provided for an export
+
+=item *
+
+OBE export was called, which is not yet implemented.
+
+=item *
+
+general I/O errors
+
+=back
+
+Errors that occur during th actual export will be collected in L<errors>. The following types can occur at the moment:
+
+=over 4
+
+=item *
+
+C<Unbalanced Ledger!>. Exactly that, your ledger is unbalanced. Should never occur.
+
+=item *
+
+C<Datev-Export fehlgeschlagen! Bei Transaktion %d (%f).> This error occurs if a
+transaction could not be reliably sorted out, or had rounding errors above the acceptable threshold.
+
+=back
+
+=head1 BUGS AND CAVEATS
+
+=over 4
+
+=item *
+
+Handling of Vollvorlauf is currently not fully implemented. You must provide both from and to in order to get a working export.
+
+=item *
+
+OBE export is currently not implemented.
+
+=back
+
+=head1 TODO
+
+- handling of export_path and download token is a bit dodgy, clean that up.
+
+=head1 SEE ALSO
+
+L<SL::DATEV::KNEFile>
+L<SL::DATEV::CSV>
+
+=head1 AUTHORS
+
+Philip Reetz E<lt>p.reetz@linet-services.deE<gt>,
+
+Moritz Bunkus E<lt>m.bunkus@linet-services.deE<gt>,
+
+Jan Büren E<lt>jan@lx-office-hosting.deE<gt>,
+
+Geoffrey Richardson E<lt>information@lx-office-hosting.deE<gt>,
+
+Sven Schöling E<lt>s.schoeling@linet-services.deE<gt>,
+
+Stephan Köhler
+
+=cut