Re: Repeat M-N times

[James Clark <jjc@jclark.com>]

Josh Lubell wrote:
> 
> I am working on reformulating data models from ISO 10303 as XML. ISO 10303
> (a.k.a. "STEP") is a standard for representing the physical and functional
> characteristics of a product throughout its life cycle. STEP is currently
> being used for data exchange between CAD systems in the automotive,
> aerospace, and electrical components industries. STEP is also beginning to
> be used in product data management (PDM) systems.
> 
> The need to repeat items between M and N times comes up pretty often in
> STEP, particularly when the data involves geometry information. For example,
> a polygon is represented in STEP as a list of three or more cartesian
> points. The control points in a b-spline curve are represented as a list of
> two or more cartesian points. A cartesian point's coordinates are
> represented as a list of either one, two, or three real numbers. Numerous
> other examples exist.

Thank you.  This was just the sort of example I was looking for.  Do you
have any feeling for which of the following are most common:

> > - repeat N or more times, where N > 1
> > - repeat between 0 and N times, where N > 1
> > - repeat between 1 and N times, where N > 1
> > - repeat exactly N times, where N > 1
> > - repeat between M and N times, where 1 < M < N

?  You mentioned the first and last.  How about the second and third
cases? Are they common?

> It appears to be the case in STEP that M and N, when specified, tend to be
> small.

Could you quantify this at all?  What is the largest M or N you have
encountered?

James