For summoning of suspects/persons accused: Art 12 para 2 of the European Convention on Mutual Assistance in Criminal Matters (20.04.1959) applies.
For summoning of witnesses: Art 12 of the European Convention on Mutual Assistance in Criminal Matters (20.04.1959) applies as well as Art 52 CISA. In particular, foreign authorities sending a postal summons to appear shall ensure that this does not involve a notice of penalty.
There shall be compliance with a request for judicial assistance which requires a procedure that differs from Austrian laws on criminal procedure, if this is compatible with the criminal procedure and its principles.