The manual is ready before the calc.
In our business, that's the way. The manual serves as spec of the UI as well. And you can avoid a lot of bullshit and development loops by specifying in due time what you want to achieve - taking the point of view of future users.
CLA isn't necessary if you use a string literal without the "append" character. It was only necessary when using XTOA because that function appends to the alpha register rather than replacing its contents.