| # buf = VFS_PAGE_SIZE, afs-cons(dirs, files), m ∈ files ⊦ ⟪choose err0 with ⌊err0⌋ in err := err0⟫ true |
# buf = VFS_PAGE_SIZE, afs-cons(dirs, files), m ∈ files, ⌊err0⌋ ⊦ ⟪err := err0⟫ true
# buf = VFS_PAGE_SIZE, afs-cons(dirs, files), m ∈ files ⊦ ∃ err0. ⌊err0⌋