Default Override column

[Lofton Henderson <lofton@rockynet.com>]

Hi all,

http://www.oasis-open.org/committees/download.php/25270/Attributes_Table.pdf

I want to be sure that I understand the "Default
Override" column.

I had thought that our intention here is to give a well-defined default
in cases where the default is "fuzzy".  For example, in
Line Cap, the V3 default is "1 (unspecified)".  And WebCGM
effectively says "any one the standardized values 2,3,4" 

Conversely, we do not intend to give access to overriding well-specified
defaults.  Correct?

So the "override" would actually be more of a default
specifier, that allows you (for Line Cap example) to choose 2 or 3 or 4
for the initial metafile display.

I don't understand a couple of entries:

-- Line Type Initial Offset is listed as "Yes".  CGM:1999
Chapter 8 (Defaults) is clear:  0.0.  Also, LTIO is not dealt
with in T.26.7, where all of these other things are handled.

-- same for ETIO.

-- Line & Edge Type Definition (LETD):  it is listed as
"Yes".  The rationale of a "default-override"
LETD would seem to be a little different than Line Cap, for
example.  Might be useful, but I haven't thought much about possible
usage scenarios.  (Note also:  LETD element defines one
negative index at a time; and it is a Picture Descriptor
element.)

-- Hatch Style Definition (HSD):  same comments.

Otherwise, I don't have issues with the list of default-override
candidates.  

Question:  Do we want to give selective access (like the selective
Style Properties access that we seem to support)?  Or should we take
the "do 'em all" approach on this functionality?  (Again,
this can probably be treated as a 2.1 design question, once we say yes or
no to the general functionality.)

(Aside.  In my yesterday message, I overlooked that LETD and HSD are
Picture Descriptor elements.  That doesn't necessarily invalidate
their manipulation as Style Properties, but will raise some design
questions when we get there.)

(Another aside.  Yesterday I said that applicability of LTIO to line
types 1..5 and 6..15 was dubious.  In fact I checked CGM:1999 and
there is no such restriction, it is apparently applicable to the
predefined ones, just as it is to LETD-defined ones.)

-Lofton.