m n u v x y are special and used by J utils in certain cases.
There is nothing stopping you using them but if you do some strange and
unexpected behavior may happen and you have been warned.
They are not reserved as globals and there has no bug in recent threads
about them.
Older examples in older books may have used them in a way that cause some
utils to report differently from what they did.
They are not bug in the interpreter and they are not bugs in the old books
because they were/are ok for older versions og J.
This discussion is in part a bit silly.

2011/9/26 The Geeko <[email protected]>

> Raul Miller <rauldmiller@...> writes:
>
> > I believe that any use of m n u v x y as globals, in books, should be
> > considered a bug and reported to the author.
>
> I beg to differ with you on this point.  From pouring through the
> Dictionary[1]
>  (i.e., its very definition), there is no mention of reserved global names,
> other
> than those which are defined by the language.
>
> This is why, for example, the language elements like Integers ('i.'), Memo
> ('M.'), and Symbol ('s:') are defined with 2 characters[2].  This makes for
> a
> very smart grammar which does not need to *reserve* words unnecessarily
> and,
> therefore, permits the language to be thoroughly expressive.
>
> It is also, I am guessing, the reason that[3] x and y were earlier
> designated as
> 'x.' and 'y.'.  It is this last fact that explains why so many books
> include 'x'
> and 'y' as global words.  And rightly so, imho.  By not reserving language
> elements unnecessarily, users are able to be more expressive and are
> required to
> remember fewer exceptions.
>
>
> NOTES
> [1] which is *presumably* the official specification for the language
> [2] an alphabetic symbol and the name-extension symbol (i.e., '.' or ':')
> [3] in previous versions of the language
>
>
>
> ----------------------------------------------------------------------
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>



-- 
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Fornustekkum II
781 Hornafirði,
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Tæknikunnátta höndlar hið flókna, sköpunargáfa er meistari einfaldleikans

góður kennari getur stigið á tær án þess að glansinn fari af skónum
          /|_      .-----------------------------------.
         ,'  .\  /  | Með léttri lund verður        |
     ,--'    _,'   | Dagurinn í dag                     |
    /       /       | Enn betri en gærdagurinn  |
   (   -.  |        `-----------------------------------'
   |     ) |         (\_ _/)
  (`-.  '--.)       (='.'=)   ♖♘♗♕♔♙
   `. )----'        (")_(") ☃☠
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm

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