It is well known that in a
locally compact Hausdorff space every countably additive measure on Rσ(𝒦δ), the
σ-ring generated by the compact Gδ sets, can be extended to a countably additive
measure on σ(ℱ), the σ-algebra generated by the closed sets. In a locally
compact Hausdorff space ℱ, the lattice of closed sets, countably coallocates
(Definition 4.7) the lattice of compact Gδ sets. Our purpose is to show that
coallocation and countable coallocation are properties basic to many extension
theorems.