  Given any uniform domain $\Omega$, the Triebel-Lizorkin space
$F^s_{p,q}(\Omega)$ with $0<s<1$ and $1<p,q<\infty$ can be equipped with a norm
in terms of first order differences restricted to pairs of points whose
distance is comparable to their distance to the boundary.
  Using this characterization, originally due to Seeger and reproven here, we
prove a T(1)-theorem for fractional Sobolev spaces with $0<s<1$ for any uniform
domain and for a large family of Calder\'on-Zygmund operators in any ambient
space $\mathbb{R}^d$ as long as $sp>d$.
