I'm trying to understand the precise geometrical transformations in
Canadian Syllabics, and I've hit a puzzle. Carrier 'syllables'
representing a vowel sign are illustrated at
http://www.unicode.org/charts/PDF/U1400.pdf codepoints 1401, 1402,
1405, 1408 to 140A, 142F, 1431, 1433, 1436 to 1438, 15C4 to 1614, 1616
to 1619, and 161B to 166C and at
http://www.ydli.org/dldocs/syllipa.pdf (by Poser). Like the best
known class of syllables in Cree, all syllabics in Carrier are
basically related by rotation. This works fine for the symbols that
are symmetric about the pointing direction (left for /a/, right for
/@/ - and thus /e/ and /i/, up for /o/ and down for /u/). For symbols
with asymmetry at the rear, namely those for vowel plus consonants
/n/, /m/, /j/ (/y/ in American, CARRIER YU etc. in Unicode), /tS/ (/j/
in American, CARRIER JU etc. in Unicode) and /tS`/ (CARRIER JJU etc.
in Unicode), those pointing horizontally and vertically are reflected
about the axis of symmetry relative to one another. This in itself is
not a problem.

However, the symbols with an asymmetry to one side are a puzzle.
These are the ones for consonants /l/, /tlh/ (American /tl/, Unicode
CARRIER TLHU etc.), /tl/ (American /dl/, Unicode CARRIER DLU etc.) and
/tl`/ (American /tl'/, Unicode CARRIER TLU etc.). The Unicode chart
shows the left- and right-pointing syllables as having the projection
jutting out upwards, as does the Aboriginal Sans ('absans') font
(available from http://www.languagegeek.com/font/fontdownload.html ).
However, Poser's font shows /tlhe/ and /thli/ (but not /tlh@/!) as
having the projection pointing down. Things become even more
confusing for the /u/ and /o/ vowels:

Jutting left:
Unicode: /lu/, /tlho/, /tlu/, /tl`o/
Absans: /lu/
Poser: /lu/

Jutting right:
Unicode: /lo/, /thlu/, /tlo/, /tl`u/
Absans: /lo/, /thlu/, /thlo/, /tlu/, /tlo/, /tl`u/, /tl`o/
Poser: /lo/, /thlu/, /thlo/, /tlu/, /tlo/, /tl`u/, /tl`o/

As you can see, the Aboriginal Sans script agrees with Poser, for the
/u/ and /o/ vowels. For /tlhe/ and /thlhi/, it has the projection
pointing upwards.

What's happening here? Have the Unicode charts got it wrong? Is the
choice of position free?