🚀 go-pugleaf

leslie@book.dle.dg.com (Leslie French) asks:
   Does the direction of a hint make a difference, i.e. is there any
   difference between (say)

           150 -10 hstem    and    140 10 hstem

   if so, what? I've seen both 'positive' and 'negative' hints generated
   for a single character, and I'm curious as to whether or not there's a
   reason behind it.

First, you  must understand that Type  1  hinting is  declarative by nature
which means, as the Black Book ("Type 1 Font Format") points out, the "hint
system depends  on  an intelligent  rasterizing  algorithm to   render  the
character  outlines...  [and that   c]onsequently the   appearance  of font
characters  created  with  declarative hints will...     [change]   as hint
handling algorithms [change]." (p. 36)

Therefore, the answer to your question is "it depends on which interpretter
you are using" because different implementations will, by design, interpret
the hints differently.

However, two possible differences might be: (1) only part of the stem might
lie in  a BlueValue zone  and perhaps the zone  snapping  is activated only
when the stem starts/ends in the zone, or (2)  since the "from" end  may be
anchored before the "to"  end (e.g., "from 140 to  150" vs.  "from  150  to
140"), the "from" end is likely to have a more accurate placement while the
"to" end is likely to have a less accurate placement.
-- 
Adam Grossman
arg@bitstream.com