12.4 Backslash-Newline-Newline in Make Macro Values

On some versions of HP-UX, make reads multiple newlines following a backslash, continuing to the next non-empty line. For example,

FOO = one \

BAR = two

test:
        : FOO is "$(FOO)"
        : BAR is "$(BAR)"

shows FOO equal to one BAR = two. Other implementations sensibly let a backslash continue only to the immediately following line.