In the document "1C:Enterprise 8.3. Developer Guide" in chapter 15 about the DATA EXCHANGE MECHANISMS an example XML representation for a Document.CustomerOrder object is shown.

Where can I find a list of these "standard" XML representation documents? Is there an example available for e.g. invoices,or master data exchange like customer or suppliers (vendors)?

Background is that I search for a documentation how the xml formats should look like to import data from another system to 1C.

Objects will have different representation because each object will have attributes, so I think it would be easier for you to implement both export and import in 1C, see file formats and provide same in another system.