The zero tempered distribution has empty conic singular support: any p lies outside Css 0.
The Fourier transform of zero is zero, so its conic singular support is empty.
Subadditivity of the conic singular support: if p ∉ Css u₁ and p ∉ Css u₂, then p ∉ Css (u₁ + u₂).
If p lies outside Css u, then (p, q) lies outside WFsc u for any boundary pair (p, q).
If q lies outside Css (𝓕 u), then (p, q) lies outside WFsc u for any boundary pair (p, q).
Subadditivity of the scattering wavefront set: if (p, q) ∉ WFsc u₁ and (p, q) ∉ WFsc u₂, then (p, q) ∉ WFsc (u₁ + u₂).
If (p, q) ∉ WFsc u, then u decomposes as u₁ + u₂ with p ∉ Css u₁ and q ∉ Css (𝓕 u₂).
Equivalence (Melrose Thm 12.18-style): (p, q) ∉ WFsc u iff u decomposes into pieces avoiding p in physical and q in Fourier conic singular support.