Re: [office] Unicode relative spaces -- Was,

["David A. Wheeler" <dwheeler@dwheeler.com>]

marbux wrote:
> > On adding support for the em-based system of measurement to the spec,
> > I'm not sure  I understand your question as to reference size. For the
> > currently selected font, the reference size would be the horizontal
> > width equal to the font's vertical type size in points, exclusive of
> > any vertical padding between lines. So in 9 point type the em is 9
> > points wide, in 18 point type it is 18 points wide, etc.

Lars Oppermann:
> I played around a bit with emspaces inserted into the text-content of an 
> ODF file in OpenOffice.org and it seemed to work well....
> With reference-size, I meant the actual point-size with which the 
> em-space gets rendered when the document is viewed. This is obvious in 
> some parts of documents like paragraph....
> For other parts of a document, this is more difficult. For instance page 
> margins - There is not normally a font-size associated with a page. 
> Paragraph styles are associated with master-page styles which are linked 
> to page-layouts, but not the other way round (see sect. 2.8, 14.3 and 14.4).
> 
> I can see how em-based horizontal measurements can be useful in text 
> documents. However, just calling to allow them wherever cm, in, pt etc. 
> are allowed is not feasible. From reading your clarifications I can see 
> that you don't want to do this.

Yes, I think we're all seeing the same problem: em-measurements require that you know what the current font size _is_.

But I think it'd still be very useful to include this measurement system; there are cases when you want relative not absolute measures. Why not note here that "em" is also permitted in some cases, and then later on note the cases where this is portable (so don't put it elsewhere in portable documents)?

The fact that other document formats (e.g., CSS) include em-measurements is a good argument for its utility.  In general, OpenDocument is much more general and is a superset of the capabilities of other documents.  This is one narrow exception (the lack of em-measurements) which I'd like to get rid of.

--- David A. Wheeler