Gel patterns

[Richard Durbin]

I like the option of Bands or Band.  I agree that Text following float
does not have to be UNIQUE -- I just thought that by default only the
first would be used as an explicit label.

But removing the ?XXX makes an important difference.  As you have it, wiuth
	Gel #Gel_Pattern
you can only attach one pattern to an object.  This is because the #Gel_pattern
is a unique subobject.  You could have two Probe entries in it and two Bands, 
but there would be nothing to attach one set of bands to a particular probe.
The alternative
	Gel ?XXX #Gel_Pattern
lets you attach a label to each gel_pattern, so you can differentiate them.  It
is very important.  Of course in any one model you would have, e.g.
	Gel ?Text #Gel_Pattern
but I thought that the DtGelPattern code might as well not care about the
class of this first key -- just use it as a label.  You could even have a tag:
	Gel Line1_fp #Gel_Pattern
	    Line2_fp #Gel_Pattern
	    Alu_pcr #Gel_Pattern
In fact, I imagine that this could well be the most common usage.  The .ace
file would then say:

Clone F37C3
Line1_fp Bands 2.3 4.8 4.9 15.6
Alu_pcr Bands 1.3 17.6 26.1

So I argue strongly that you are not using your marvellous invention of the
second tag system in your proposal.

Everything else looked good.

Richard