After a lot of messing I think I've cracked it!

Based on a import of a "Supplier Purchase Receipt"

From countless tests, doing exports of existing data, looking through the database and a bit of jigury pokery, I came up with the following table which shows how names and values can change, and hence my confusion over the values to use.

As you can see the the export method is almost there, but not quiet, plus a bit of guesswork knowledge of knowing to include the "account_id" and "type".

I found having to export the data, interpret it tedious. So...

My preferred way of mapping the data is to "activate the developer mode" then "create a new form" then by "mousing over" each field you are told the "Field" name, which is the correct import name to use! The lines are a bit more difficult - first obtain the field name (eg line_dr_ids) then select "add an item" then obtain the rest of the field (eg account_id) then join them together to give your name (eg line_dr_ids/account_id). You still need a bit of psychic wisdom to know to include "account_id" and "type", by "vaildating" the imported csv, OpenERP will guide you through this! I included "tax_amount" because it easy to include and it help a bit with validating the purchase receipt later.

Hope this helps you out and saves you some time! if so give me a "vote"!