in an earlier message, i said
... the model we used for the
blackboard bold in the msbm font was a set of shapes we had been
using previously in another system, created by a u.s. company.
i am not sure specifically what they used for a model, but it
would not surprise me if it were some traditional typographic
in-line or open face typeface.
and michael points out, partly correctly, that
... I overheard at the time that the
so-called blackboard bold font in msbm is merely a disemboweled Times
Roman bold, as that was precisely what the AMS asked of the font
ams did ask that the overall shapes and weights of the letters be
compatible with times bold, since that is what we intended to use
in our journal and book production. but if there was any doubt,
the locations of the doubled strokes were to conform to what had
been used by the typesetting system we had been using previously,
a system developed by science typographers (sti), and which had
been reimplemented in msym (in a not particularly refined manner;
some strokes that should have been parallel were not, and there
were other very bad flaws in that alphabet, though not in the
original sti implementation. since i created the first few
letters for the msym \Bbb -- using the sti openface as a strict
model -- as part of my attempt to learn mf79 under knuth's
tutelage, i am abundantly aware of their limitations).
i assure you that the doubled strokes in msym, in the sti openface
font, and in msym are all in exactly the same places -- i checked
all three from contemporaneous source documents before replying.
i will be happy to produce the evidence, which is part of my
as you see from my original statement, i don't know what sti used
for a model -- it may very well have been an inline version of
times or century -- but in fact we used that font at ams from
probably about 1973 until about 1983, and the doubled lines were
*always* in the same locations in each letter as what's in msbm,
quite different from what's in bbold.
i too am sorry that there's not more commentary in the mf code,
but since i installed the original sti font here at ams, and was
somewhat involved with the development of both msym and msbm, i do
know for sure what i've stated above about its provenance.