1. A computing device that implements a business process management system, comprising: a processor; memory in electronic communication with the processor; a parent workflow process stored in the memory; a child workflow process stored in the memory, wherein the parent workflow process includes a call to the child workflow process, wherein the parent workflow process comprises a first action and a second action, wherein the child workflow process comprises a third action and a fourth action, and wherein the actions are executed initially in the order of the first action, the second action, the third action and then the fourth action; and a workflow engine that is configured to execute within a thread of execution the parent workflow process and the child workflow process, and that is configured to determine an undefined characteristic of the child workflow process with reference to data that corresponds to the parent workflow process in order to continue execution of the child workflow process, wherein the characteristic is a value of a field or a behavior of an action, wherein determining the undefined characteristic of the child workflow process comprises traversing the thread of execution in a reverse direction until the data is located that allows the undefined characteristic of the child workflow process to be defined, wherein traversing the thread of execution in the reverse direction comprises going back to previous actions starting at the fourth action in the order of the third action, the second action, and then the first action.