Cli and transaction customfields


I’m running RT 3.6.1 on debian

I am attempting to automate a number of tasks using the CLI.
How can I use the CLI to add a comment to a ticket that has
CustomFields setup for ticket transactions. In reading the docs I
have not discovered how to refer to a transaction CF via the CLI

I can add a comment with the following

rt comment -m “comment goes here” ticket/9999

I have set up a number of CF’s for ticket transactions.
The CLI appears to happily refer and set a transaction CF but the
result seems to end up as a ticket CF. Checking the database the CF
content refers to the ticket number when it should refer to the
transaction number.

rt edit ticket/9999 set CF-trnCF=“blah”

Any assistance would be most appreciated.