Unicode -- bidirectional layout algorithm

From: Patrick Stephens (pstephen@informix.com)
Date: Wed Jul 31 1996 - 03:40:04 EDT

(Apologies if you already received this)

Hi, a bididirectional text layout question...

What is the correct display order of the logical sequence
when the global direction is right-to-left.

ref. the Unicode Standard V1.0 Volume 1, page 618, "Resolving Implicit
    "if the global direction is odd (right-to-left) then the
    left-to-right text and numeric text (EN or AN) goes up one level".

In this case the embedding levels for the above sequence are "122".
After reordering level 2 this gives
and after reordering level 1 gives the final result

Microsoft Arabic Windows displays this sequence as
when the reading order is right-to-left (I assume that global direction
is the same thing as reading order).

Who is right? Arabic Windows supposedly implements the Unicode algorithm.

Arabic Windows and Unicode agree on the layout of this
sequence when the global direction is left-to-right, ie


Patrick Stephens                        direct: (01)405-1123
European Development			switch: (01)405-1000
Informix Software Ireland Ltd.          fax: (01)405-1140
email: pstephen@informix.com           	international: +353-1-405-(as above)

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