Good Day.

I'm a developer of a trucking management software (LoadCon Manager) that captures all related day-to-day activities (Loads, sales invoicing, vehicle maintenance and supplier invoicing, employee payroll and control accounts).

I need to export this data into Pastel. I have searched this site and stumbled upon several threads and downloaded this file: Import_Export_File_Layouts_-_General_Ledger_Journal_and_Cashboo.pdf
which is exactly what I'm looking for, but I need some more information to make my situation work and for me to understand what I'm doing.

In the PDF file:
Ref 1 Period 1-13 --> what do they mean ?
Ref 3 GDC (G - General Ledger, D - Customer, C - Supplier) -->> When will I use G, D or C ?
Ref 8 Tax Type 0 No tax -->> what are the other options? I will definitely be using VAT.
Ref 10 Open Item -->> the PDF file shows an extended explanation - but I have no idea what it means.
Ref 11 Projects Code -->> How is this used ?
Ref 12 Contra Account -->> What is this ?
Ref 15 Batch ID -->> How is this used ?
Ref 18 Home Amount -->> Is this: Amount minus Discount Amount ?

Is there perhaps a document that I can view that explains the import format in more detail ?

Another question: Say I import a csv file from a particular supplier into pastel for a particular date range. When I re-import the same file again, will the information be duplicated in pastel ? - or is there some logic that will prompt for duplication - or is this where 'Ref 8 Reference' (PDF file) comes into play?

Cheers. Hope I'm not too confusing.
Please note that I have no knowledge of Pastel usage and operations. However I have a general background on accountancy principles.

Thanks in advance
Alex