[cgmopen-members] NUBS/NURBS defect from before..

["Cruikshank, David W" <david.w.cruikshank@boeing.com>]

Lofton (et al),

I think this goes back a couple of years....there was part of the NUBS/NURBS
defect that was not implemented in CGM:1999.

It had to do with the Abstract Specification area:

In 7.6.24 NON-UNIFORM B-SPLINE

The last sentence in the 2nd paragraph says:
"The end value shall be less than the n-th knot value (where n is the number
of control points)." 
And in 7.6.25 NON-UNIFORM RATIONAL B-SPLINE

The last sentence in the 3rd paragraph says:
"The end value shall be less than or equal to the n-th knot value (where n
is the number of control points)." 
Neither of these is correct.  They both should say:
"The end value shall be less than or equal to the (n+1)st knot value (where
n is the number of control points)." 
I think, with the help of Dick Fuhr, we identified this deficiency about two
years ago. CGM Open carried an action to create the defect and forward it to
SC24.  I think it was assigned to John, since he was our liaison at that
time.  John left about the same time and the action fell to the wayside.

How do we get this defect transmitted to SC24 and back into the system?  We
have run into a case where the current wording in the Standard was
implemented and, as a  result, we cannot generate what we consider a
"correct" NUB.

thx...Dave

Technical Fellow - Graphics/Digital Data Interchange
Boeing Commercial Airplane
206.544.8876, fax 206.544.9590
david.w.cruikshank@boeing.com