When a related action is initiated from a record, Appian passes contextual data from that record into the designated process model. This data is received as process parameters, which are then stored and accessed within the process instance as process variables. The pv! domain prefix is the correct syntax used in Appian expressions to reference these process variables throughout the process model's lifecycle.

A. ac!

This prefix references activity class parameters, which are variables scoped to a specific node (e.g., a user input task) within a process model, not the overall process variables.

C. rv!

This prefix is used exclusively within the record view's interface definition to reference the record's data (e.g., rv!record). It is not used within the process model itself.

1. Appian Documentation, Process Variables: "Process variables are used to store data that is used by a process. They are referenced using the pv! domain... Process variables are defined in the process model properties." This confirms pv! is the domain for data at the process level.

2. Appian Documentation, Configure a Related Action: In the "Configure the action context" section, the documentation illustrates passing record data (like the identifier) into a process parameter. Once inside the process model, this parameter becomes a process variable, accessible via pv!. For example, a parameter named recordId would be referenced as pv!recordId.

3. Appian Documentation, Expression Language: This page lists the various domain prefixes and their scopes. It explicitly defines pv! for Process Variables, ac! for Activity Class Parameters, and rv! for Record View variables, clarifying their distinct contexts of use.