Considering High Level Interlinear Text Requirements

Greetings All,

At this point there may be only two of on the mail list.  Though more have
expressed interest in enhancing interlinear text support in w3c standards,
there is likely a lack of awareness that the group has formed -so get the
word out :-)

I thought I would start a conversation on very high level requirements for
interlinear text as it relates to base text.  From observation, interlinear
text has at least two alignment associations:

1) Anchored start:  The interlinear text is "anchored" or "bound" to one or
more contiguous letters in the base text.  The interlinear text aligns at
the anchor point and continues to its end, which may span one or more base
lines.

2) Anchored start and end: The start and end points of interlinear text are
each anchored to one or more contiguous letters in the base text. The
"margins" of the IL text are within the start and end anchors.  Alignment
(left, right, center) and letter distribution of the IL text is also
specified (e.g. CSS ruby-align attribute values).

These definitions should be valid for both RTL and LTR text.  Ruby and
Zaima interlinear text would fall under the "Anchored start and end"
category.  Ruby, and even more so Zaima, annotation practices are what I am
most familiar with -and little else.  The "Anchored start" (1), with no
fixed end point I gather is essential to other interlinear use cases.

Thoughts? Is there another high level requirement?  Is interlinear text
ever fully independent of the content of the base text?

cheers,

-Daniel