Hi Andy,
So your requirement is to have different default text in ZS14 text type for different condition,The special product IDs you mention are in the header level? Can you pls explain some more on the special condition you have?
I am not sure if this can be done via only config. There are two options I can think of, I am not sure if they will work, but worth a try.
1. In the FM , used in the text determination procedure, which reads standard text, maybe you can put a condition and read different standard texts based on that condition. This FM gets triggered as soon as the activity is created, you can try to check if there is any way get the parameters of the condition you need.
2. Create a complete custom solution for this, you can take a look at creating a new event for your requirement, say for example AFTER_CREATE of ORDERADM_H and in that callback event write the code to default your note using CRM_ORDER_MAINTAIN.
~Anupam