[PDF's] they can be used properly as containers
for multiple-component
documents
Even better, if the original document truly is a vector drawing (lines,
arcs, filled areas, text) then PDF is a really good choice for
showing it around (of course, Postscript and SVG are good too).
Rasterized renderings are so clunky compared to a vector graphic
that you can zoom in on and get infinite resolution no matter what your
zoom level.
This doesn't cover many scanned documents, though. Vectorizing a
scanned schematic would probably be slow and error-prone, especially
if there is any noise in the original. But maybe someday it can be
done.
Tim.