From a google-search: There are non-formal exchanges between a lawyer and a judge on a case. An official subpoena/summon may therefore well be called a förmliche (Vor-)Ladung. The term in brackets after the name of the lawyer may therefore just signify that the hearing is official and said lawyer is summoned to appear in person.
From your other posts I can tell that something happened in your case and your lawyer (along with you?) is now summoned to appear in person on another date than previously scheduled.