This is a study of the behavior of wave equations in conformally compactified
spacetimes suited to the use of computational boundaries beyond Scri+. There
light cones may be adjusted for computational convenience and/or Scri+ may be
approximated by a "proto-Scri" spacelike hypersurface just outside a de Sitter
horizon. One expects a numerical implementation to excise the physically
unnecessary universe somewhat beyond the outer horizon. As an entry level
example I study forms of the Maxwell equations and causal relations for an
outer boundary in that example.Comment: 5 pages, no figures; added acknowledgements and references in v
