Short answer
Upper-chest canvas padded lightly where the body is quiet and cloth would otherwise fold.
Why it happens
Upper-chest concavity beyond the block.
Why ready-to-wear cannot fix it
Size charts grade uniformly; prominent collarbone area is a personal geometry. A block adjusted in one place pulls in another — which is why the correction must exist in the pattern, not in the fitting-room mirror.
How the house drafts for it
Upper-chest canvas padded lightly where the body is quiet and cloth would otherwise fold. The correction is recorded in your Fit Passport, so every later commission starts from it automatically.
Where it matters most
This correction carries most for: suit, tuxedo. It is reviewed at every fitting, in every city, for every garment.
Fit Library entry 37 of 48 · Reviewed by Bonturberg Editorial Review · 2026-09-08