Digital documents have become an integral part of our society. However, the basis of the retention and evidence rules is still largely formed by those of paper documents. The starting point for documents (both paper and digital) and the establishment of a digital archive are always threefold:

• Assure readability: both now and in the future, the readability of a document must be assured. Here the authenticity of the document (e.g. supplier clearly on invoice) must be assured.
• Unchangeable (in time): the content of a document (e.g. invoice) cannot be changed or copied. This characteristic is thus primarily applicable to originals that bear a signature. To ensure immutability, a user can, for example, choose to attach certificates to individual documents. This attaches an immutable time lock to the document, a digital stamp or signature as it were.
• Stability and sustainable character: where a durable data carrier is seen as "a device that (...) enables a person to store information in a way that makes this information accessible for future use for a period of time appropriate to the purpose (...)"(Article I.1, 15° of the Economic Code).

The digital document is also sufficient for control or audit purposes, provided that the above conditions are met and that the data can be easily consulted.