Hi Štěpán and Branden!
On 7/30/22 16:15, Štěpán Němec wrote:
Hello Branden,
On Fri, 29 Jul 2022 15:58:23 -0500
G. Branden Robinson wrote:
-The VFS imposes limitations that an attribute names is limited to 255 bytes
-and an attribute value is limited to 64\ kB.
+The VFS-imposed limits on attribute names and values are 255 bytes
+and 64\ kB, respectively.
While you're tidying this up, I would convert the `\ ` escape sequence
to `\~`. Both are non-breaking spaces, but the latter is adjustable.
groff_man(7) from groff 1.22.4 says:
\~ Adjustable, non-breaking space character. Use this escape to
prevent a break inside a short phrase or between a numerical
quantity and its corresponding unit(s).
Before starting the motor, set the output speed to\~1.
There are 1,024\~bytes in 1\~kiB.
CSTR\~#8 documents the B language.
Thank you for the review!
I think I disagree: IMO a number+unit should be treated as a single
entity both semantically/logically and typographically (at least as far
as space stretching goes), i.e., say (if I understand the effect of '\ '
and '\~' right),
255 bytes and 64 kB, respectively.
would make a bit more sense to me than
255 bytes and 64 kB, respectively.
Current Linux man-pages usage doesn't appear quite consistent, but '\ '
prevails over '\~' (about 6:1), and my cursory grep found only one
instance of '\~' used between a number and its unit
Would you mind sensing a patch for that one between the number and its unit?
(vs. many instances
of '\ ' in that context).
That is just a matter of writers not knowing the existence of \~ ('\ '
was documented in man-pages(7), but \~ wasn't). I wouldn't give much
more importance to existing practice in this regard.
When I read this email I had no strong opinion; both variants made sense
to me. So I did some investigation, to see if the SI already specifies
something about it; and it does:
<https://www.bipm.org/en/publications/si-brochure/>:
[
5.2 Unit symbols
Unit symbols are printed in upright type regardless of the type used in
the surrounding text. They are printed in lower-case letters unless
they are derived from a proper name, in which case the first letter is a
capital letter.
An exception, adopted by the 16th CGPM (1979, Resolution 6), is that
either capital L or lower-case l is allowed for the litre, in order to
avoid possible confusion between the numeral 1 (one) and the lower-case
letter l (el).
A multiple or sub-multiple prefix, if used, is part of the unit and
precedes the unit symbol without a separator. A prefix is never used in
isolation and compound prefixes are never used.
Unit symbols are mathematical entities and not abbreviations. Therefore,
they are not followed by a period except at the end of a sentence, and
one must neither use the plural nor mix unit symbols and unit names
within one expression, since names are not mathematical entities.
In forming products and quotients of unit symbols the normal rules of
algebraic multiplication or division apply. Multiplication must be
indicated by a space or a half-high (centred) dot (⋅), since otherwise
some prefixes could be misinterpreted as a unit symbol. Division is
indicated by a horizontal line, by a solidus (oblique stroke, /) or by
negative exponents. When several unit symbols are combined, care should
be taken to avoid ambiguities, for example by using brackets or negative
exponents. A solidus must not be used more than once in a given
expression without brackets to remove ambiguities.
It is not permissible to use abbreviations for unit symbols or unit
names, such as sec (for either s or second), sq. mm (for either mm2 or
square millimetre), cc (for either cm3 or cubic centimetre), or mps (for
either m/s or metre per second). The use of the correct symbols for
SI units, and for units in general, as listed in earlier chapters of
this broch ure, is mandatory. In this way ambiguities and
misunderstandings in the values of quantities are avoided.
]
[
5.4.3 Formatting the value of a quantity
The numerical value always precedes the unit and a space is always used
to separate the unit from the number. Thus the value of the quantity is
the product of the number and the unit. The space between the number
and the unit is regarded as a multiplication sign (just as a space
between units implies multiplication). The only exceptions to this rule
are for the unit symbols for degree, minute and second for plane
angle, °, ′ and ′′, respectively, for which no space is left between the
numerical value and the unit symbol.
This rule means that the symbol °C for the degree Celsius is preceded by
a space when one expresses values of Celsius temperature t.
Even when the value of a quantity is used as an adjective, a space is
left between the numerical value and the unit symbol. Only when the
name of the unit is spelled out would the ordinary rules of grammar
apply, so that in English a hyphen would be used to separate the number
from the unit.
In any expression, only one unit is used. An exception to this rule is
in expressing the values of time and of plane angles using non-SI units.
However, for plane angles it is generally preferable to divide the
degree decimally. It is therefore preferable to write 22.20° rather
than 22° 12′, except in fields such as navigation, cartography,
astronomy, and in the measurement of very small angles.
]
Sorry for copying the full text, but I preferred to give enough context.
So, from the SI text quoted above, the space is not a word separator in
that context (it is for example not allowed to hyphenate between the
value and the unit even if it acts as an adjective; the SI disables
normal language rules). It is instead a mathematical symbol denoting
multiplication, and the whole value+unit is a single mathematical
expression; to me, that is better denoted with a single space, rather
than an adjustable one.
Therefore, I'd say that it makes more sense in this case to use '\ '.
In view of the above, failing any instruction from a man-pages
maintainer to the contrary, I'd prefer leaving this as is.
In the general case, I prefer \~, but for value+unit I prefer '\ '.
Thank you both!
With best wishes,
Štěpán
Cheers,
Alex
--
Alejandro Colomar
Linux man-pages comaintainer; http://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/
