| n1 = 0, avols[v][m2].mapped?, m2 < # avols[v], n1 < n, ebm-cons(avols), is-aligned(n, EB_PAGE_SIZE), is-aligned(m1, EB_PAGE_SIZE), is-aligned(n1, EB_PAGE_SIZE), v ∈ avols, n + n2 ≤ # buf, m1 + n ≤ LEB_SIZE, avols[v][m2].mapped? → avols[v][m2].fill ≤ m1, ⌊err0⌋ ∨ err0 = ESUCCESS ⊦ ⟪skip⟫ ebm-cons(avols), err0 = ESUCCESS |