using diff --ignore-all-space --left-column --side-by-side
(already aliased to diffils), compare the two versions
diffils LHS RHS > DIFF
diff uses the symbols < and > to indicate material
that is missing from one version or the other. There should be no
discrepancies of this type.
The existing discrepancies should be restricted to ones indicated by
the pipe symbol ("|").
Any instances where the gold standard is wrong should be marked for
future reference (say, by affixing three asterisks to the pipe symbol
or somewhere in the line).