Here are some examples for the illustration of the XML-based customer acknowlegement (administrative order type HAC). Please note that the examples already base on EBICS version V 3.0 (published on June 20th 2018)
For the element group <Parameter> which is optionally usable in BTF up- and download requests there is no general EBICS usage rule. In order to use this structure there must be a specific (e.g. bilateral) agreement. Otherwise requests which contain this element group are going to be rejected.
A typical case of usage (agreement for France) is using <Parameter> for a "test mode".
As illustration here is an excerpt of a SEPA credit transfer order transmitted only for test cases in France.