A transaction subprocess, denoted with a double-lined boundary, is a specialized type of subprocess. In a transaction subprocess all activities must either complete successfully or the subprocess must An Ad hoc subprocess, denoted with a tilde marker, is a specialized type of subprocess. It contains a set of activities that could be performed. Sequence flow between activities is optional in an Ad hoc subprocess. What activities are performed as well as the sequence and the number of performances is determined by the performers of the activities. During execution of the (parent) process, any one or more of the activities may be active.

The ARIS method provides the tilde marker as mini-symbol for the value Ad hoc subprocess of the attribute Subprocess type. The program will render the symbols for the Ad hoc subprocess.