I don't think this exists, but it would be really helpful to have a string module. This module would allow an external program to read strings from the canvas. I would suggest storing them in ASCII with a 0 terminator just like a C string.
For example, a string module might have the name of the current canvas. If we used a constant handle this would easily be read by an external device when the AW Designer was not running.
Another use would be for individual calibration status or serial numbers.
Model XYZ Version 2
Calibration Date 01Jan23
You are correct, we unfortunately don't currently have a string module. This has been spoken about previously and we actually already have an open ticket to add this feature (decision pending and no ETA), so I will be sure to add your request to the ticket.
I'm sure you are aware of the annotation modules, which don't ultimately satisfy your described utility, but are options nonetheless.
One thing that we've seen done before to accomplish what you are describe is using a SourceInt array with an assigned Object ID:
Obviously there is some calculation that needs to happen on the backend, but it could be useful.
Regardless, thank you for your comment and important user feedback!