doc: Finish CSV documentation

documentation/CSV File Format.md

@@ -15,16 +15,38 @@ https://business-partners.int.demo.catena-x.net/companies/test-company/ui/swagge
 - There is a special mechanism for arrays of objects like they are in the JSON API
 
 ## Header line and fields
-- The field names are derived from the JSON API at
-  https://business-partners.int.demo.catena-x.net/companies/test-company/ui/swagger-ui/index.html#/business-partner-controller/upsertBusinessPartnersInput
+- The field names are derived from the JSON API (see link above)
 - The field names for nested objects are created by separating the individual names by a dot
   - For example: The `addressBpn` field in the `address` top level entry will be named `address.addressBpn`
 - There are a few special rules:
   - The top-level `nameParts` element is created using the field names `name1`, `name2`, ... `name9`
   - The name `physicalPostalAddress` is abbreviated to `physical`
   - The name `alternativePostalAddress` is abbreviated to `alternate`
-  - There is a special notation for arrays of objects (see below)
 - The minimum neccessary fields are
   - `externalId`
-  - `name1`
   - `isOwnCompanyData`
+
+## Arrays
+The following elements of a record are arrays in the REST API:
+- `identifiers.*`
+- `states.*`
+- `roles`
+- `legalEntity.states.*`
+- `site.states.*`
+- `address.states.*`
+
+Each time, a new `externalId` is encountered, this line will become the main data source from which
+all data fields for the REST API are populated. If values are provided for fields that can be arrays
+in the CSV file, the first array element will be populated with the data from the main line.
+In order to add more elements to an array, it is possible to add lines containing further array elements
+immediately the main line. These follow-up-lines must contain the same `externalId` again and data
+for exactly one array.
+
+For example, if you want to add a second `identifiers` element, create a second line where only
+the following fields are set:
+- `extenalId` (same as in the main line)
+- `identifiers.type`
+- `identifiers.value`
+- `identifiers.issuingBody`
+If you also want to provide a second element for `site.states`, do *not* set those fields
+in the same line. Instead, create a third line with the respective values.