Runtime expressions include runtime context data and metadata that you access using the rt prefix, and 1-n per user session. You can only use runtime expressions during runtime. You cannot use runtime expressions in business rule expressions or for composing a message.
Runtime expressions enable users to retrieve any data related to the runtime context, for example:
- User's display name: rt.CurrentUser.DisplayName
- HTTP request query string: rt.HttpRequest.QueryString["ItemID"]
- Server variables: rt.HttpRequest.ServerVariables["SERVER_NAME"]
From the runtime object, you can get to the workflow instance using rt.workflowinstance.
— Hana Shtemet on 05/29/2022
can you add an example of using "rt" object to get control's value on the page. It's usable for calculations of another fields at runtime.