[tex-k] Erratum: MFbook, p. 259, 261: `range m thru n' missing

[Dominik Leininger]

Hi all,

On page C261, the first `line' after `Proofsheet information:' specifies 
labels and penlabels to accept <suffixes> as parameters, without 
mentioning the useful `range m thru n' syntax of plain MF.

The definitions of range and thru are given on page C274. However, since 
the `informal inventory' as the first part of Appendix B is intended to 
list `all the features that are available', the possibility to specify a 
range of numeric suffixes as an alternative to a list of suffixes should 
be listed here.

If the syntax using range and thru is added on page C261, consideration 
should be given to also adding them to for and forsuffixes on page C259 
because they can be used as <expressions> (even without range) or 
<suffixes> as explained on page C274. `range m through n' is 
particularly useful for the forsuffixes loop, since upto is not 
available there. The argument against adding it to the syntax of the for 
loop is that it is likely to be less efficient than using the plain upto 
macro.

Since the show command also requires <expressions>, you can do something 
like `show 1 thru 10;' or `show range 1 thru 10;'. This is nowhere 
mentioned in The METAFONTbook. However, I can't think of a use case for 
this, so maybe it's not worth mentioning, neither on page C261, `line' 
4, nor on page C274.

Overall, I think the `range m thru n' syntax should be added to the 
first `line' after `Proofsheet information:' on page C261 as well as the 
third `line' after `Loops:' on page C259. The decision whether to 
include it in the for loop or in the show command should be made by 
someone more familiar with the intended completeness/clarity tradeoff of 
Appendix B.

Best regards,

Dominik