[tz] Tab/Space Formatting Inconsistency - Asia Ver 2023c

Paul Gilmartin PaulGBoulder at AIM.com
Wed Dec 13 01:46:13 UTC 2023

On 12/12/23 17:25:15, Paul Eggert via tz wrote:
>     ...
> As Alois writes, this is merely a visual appearance issue; it doesn't affect the meaning of the data.
> .
Sometimes it matters.  "make" requires build rules to be introduced
by tabs. not spaces.  And I know a couple lexical analyzers which
recognize spaces but not tabs as separating tokens.

> Spaces are sometimes used instead of tabs, when using a tab would cause columns or lines to not fit. For example, consider the line:
>     ...
> Rule EgyptAsia    1957    only    -    May    10    0:00    1:00    S
>     ...
> We prefer data to be 80 character columns or less for the usual reasons; see, for example <https://www.emacswiki.org/emacs/EightyColumnRule>. So we use a space instead of a tab there. > .
Which says,
     “Thou shalt not cross 80 columns in thy file” originated from
     IBM 80 column punch cards, ...

On IBM 80 column punch cards, the tab, 0x05 (rarely used), occupies
only a single column, regardless of its appearance on output devices.


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