[tex-k] Typo in "TeX the program" (Volume B)

[Igor Liferenko]

Section 49 states:

  at least 81 printable characters are needed

Let's check:

Both
  '41-'46,   '60-'71
and
  '141-'146, '160-'171
code ranges are excluded from "add or subtract '100" rule, so
both these ranges must be present.

Further, '136 must be present (thus, '036 need not be present).

A total of 33 codes.

Then we need any mixture from the following two sets, to cover each
corresponding position:

  '0-'35,    '37-'40,   '47-'57,   '72-'77
  '100-'135, '137-'140, '147-'157, '172-'177

Each of these sets has 47 positions (30+2+9+6).

So, we have 33+47=80 codes. All the conditions are satisfied.

80 is less then 81.

Regards,
Igor