Re: [emergency] RE: Some comments/thoughts on EDXL) DistributionElement, v. 1.0

[Rex Brooks <rexb@starbourne.com>]

Note, my somewhat flippant reply to Carl was penned before I read 
this, and therefore is no reflection on these points, and I apologize 
if my frivolity was inappropriate. Been one heckuva looonnnng holiday 
day. While I would not insist on the changes I agree with, nor dig in 
my heels on anything, period, I don't think that these changes rise 
to the level where I would see a need for yet another 15-day comment 
period if we added the ones we agree to after the upcoming 15-day 
comment period.

Ciao,
Rex

At 2:40 PM -0800 1/16/06, Art Botterell wrote:
>Carl et al. -
>
>A few quick queries and comments...
>
>On Jan 16, 2006, at 1/16/06 2:04 PM, Carl Reed OGC Account wrote:
>>I would suggest that the correct phrasing should be "space 
>>seperated list of latitude-longitude pairs, with each pair 
>>separated by whitespace" or something along those lines. I would 
>>discourage commas as ISO, W3C, and the OGC have all determined that 
>>space separated/white space is best practice. I know that this is 
>>also a bit different that CAP, which is comma delimited.
>
>CAP uses commas within lat/lon pairs, but spaces between those 
>pairs.  Not sure I understand the distinction you seem to be drawing 
>between "space" and "whitespace." Are you suggesting just an 
>alternation of lats and lons with spaces between all... i.e., no 
>difference between the intra-pair and inter-pair delimiters?  Seems 
>like that would make converting the string into an array of lat/lon 
>pairs harder.  Maybe an example of what you mean would be helpful.
>
>>5. For Circle, why a radius expressed only in kilometers?? And 
>>there is no statement as to the precision for kilometers. Is the 
>>nearest Kilometer enough or should accuracy be properly expressed - 
>>like down to meters. We need some informational guidance here.
>
>It's in kilometers because that's the unit we decided on.  It's ONLY 
>in kilometers because we didn't want to complicate things by 
>requiring clients to know how to convert among a variety of units.  
>(Nautical miles? Leagues? Rods? Furlongs?)  It seemed more 
>reasonable to require the sender to convert from its local units, 
>once and for everyone.
>
>As for precision... the only guidance we offer in CAP is that the 
>presented precision should not exceed the actual precision of the 
>measurement.  Other than that, seems like each source should be 
>allowed to be as precise or imprecise as its information happens to 
>be.  Certainly there's no requirement that the radius be an integer.
>
>>6. For polygon, the document states, "an ordered set of vertices". 
>>This is ambigous. Is the ordered set clockwise or counterclockwise?
>
>It's not ambiguous... the vertices need to be in sequence.  We 
>discussed this for CAP and concluded that there was no actual 
>requirement to enforce a direction of ordering.... most software and 
>most algorithms seemed able to cope with either direction.  I would 
>agree, however, that we could probably be more specific about our 
>usage of the term "polygon," which refers to what ESRI calls a ring 
>(i.e., single, and non-self-intersecting.)
>
>>Some might say that the above informational guidance should be in 
>>an implementors guide. However, in terms of compliance, 
>>international standards best practice, lack of ambiguity, and so 
>>forth such guidance MUST be included in the actual standard and not 
>>in non-normative supporting documentation.
>
>Carl, we've always relied on the GIS subcommittee to give us 
>guidance on these issues.  It's regrettable that these inputs are 
>arriving so late in the process, and I guess the TC will have to 
>decide whether they justify further delay in approving EDXL-DE 1.0. 
>Anyway, not sure what your basis is for using the imperative MUST in 
>this regard... seems like we're talking about a matter of opinion 
>here.
>
>- Art
>
>
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-- 
Rex Brooks
President, CEO
Starbourne Communications Design
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