#558: /topic/gilbert/ascii-header

  - Good idea to record the field separator as well. But for non-printable
  characters (like the default tab) it looks a bit odd, and the enclosing
  `'...'` are somewhat tricky to parse as well. How about ``# separator
  \t``, with whitespace separating the two and the separator itself having
  non-printable characters escaped. Note though that (1) I'm not sure
  whether it should be ``\t`` or for consistency ``\x09``, and (2) whether
  either of these can be easily converted back into the binary form in awk.

I don't like using whitespace here. If the remainder of the file uses tabs, that's a mix of two whitespace characters :-(. How about using a colon?

With my darwin awk the following works:
    awk 'BEGIN { FS="\x09" }

  Other ideas?
  - What's the use case for including the path?

Maybe "path" is misleading. Could try with "log" or "file" instead.

  - I'm wondering whether we should make it easy to tell what kind of meta-
  line it is. How about this format:
     #fields ts uid id.orig_h id.orig_p ...
     #types time string addr port ...
     #separator \t
     #path conn