This controls how sharply the princess seam will revert back after having added the extra volume for your chest.
A picture says more than a thousand words, so here's the option sampled on the relevant part of the pattern:

As you can see, the option controls the urgency with which the princess seam reverts back to your waistline
after passing the fullest point of your bust.
A low factor will make for a more fitted coat, but also a more curvy seam that is harder to sew.
A higher smooth factor will smooth this out so it's a more sloped retreat to the downward seam.
This will make the coat less fitted under your chest, and the seam easier to sew.
## A reminder about made-to-measure patterns
This goes without saying for regular visitors to this site, but if you're new here, it's worth repeating:
> This coat is not drafted with a certain cup size in mind. Instead, it will adapt to your chest based on your measurements.
## Ladies, we need your feedback
This is our first womenswear pattern with a fitted chest.
As such, we're breaking new ground here, and I'd be interested to see how this pattern adapts to a variety of body shapes/cup sizes.
If you're planning to make this coat, or a muslin of it, please share your experience, and don't hesitate to get in
touch should you run into any issues.
I plan to design more womenswear patterns, so if there are any fit issues, I'd like to know about it sooner rather than later.
## Shout-out
Last but not least, I'd like to thank [Anneke](http://www.annekecaramin.com/) for her help throughout this project, and tolerating my countless rants about