http://ozreport.com/18.055#0

From the new prototype rules (as found in the local rules for the pre-Worlds):

Prototypes are allowed in test competitions (Cat. 2), but not in
the World Meet (Cat. 1). The new prototype control rules have been adopted and
will be in effect for the World Meet in 2015.

Prototypes are gliders that are outside the manufacturer’s tolerances of
specifications or construction plans as published.

Measurement tolerances will be those provided by the manufacturer or .05% (.0005
times the length). Battens must be as true to the glider’s published pattern as
possible.

I was able to sit down with Steve Pearson in the Oz Report World
Headquarters and discuss at some length this new prototype measuring rule. He
referred to batten length, casually mentioning that he doubted that the T2C
batten chart was accurate enough to be used as a template to measure actual
battens against, at least not to .05%.

You might note that all but two of the battens on the T2C and other gliders are
adjustable. This presents a problem right away, as which length are we talking
about. But it doesn't stop there.

So I made a measurement of my most outboard adjustable Wills Wing T2C 144
batten. It's hard to get a "good" measurement of the batten with a steel tape
measure as it has to bend around the curvature of the batten and it is difficult
to get it to bend just right. So there is quite a bit of slop in the measurement
to begin with so remember that when I publish here the lengths I measured with
spurious precision.

The batten length is 45.1875 inches which precisely equals: 147.763 mm (that was
a conversion, not measured with my MM steel tape measure).

The foot/inch steel tape measure seemed to measure 45 3/16" (thus the decimal
value above).

Let's assume for a moment that this is the Wills Wing specified length (this
assumption won't matter for the purposes of our example).

If I want the batten length to be within .05% of the length we'd find this
distance to be: .02259375 in (about 1.4 64th's of an inch) or .0028694075 mm.

Now, unfortunately, the measurement was made with the flip tip end rotated 180
degrees. When I rotate the tip so that I can install the batten it is out of
tolerance. No matter which way I turn it it is either too long or too short. (I
assume that this is the case as Steve Pearson tells me it is. My measurement
device is too crude to be able to measure the distance difference between the
two half rotations but I'm following Steve in that it is greater than .02259375
inches.)

Now the current CIVL prototype rule requires that measurements be able to
distinguish lengths within .05% of the "published" lengths. This would suggest
that that is going to be too difficult.