Data Dictionary, some clarification, and the way forward.

[Ian Lowe]

After today's input from Paul, and some lengthy conversations, we have what
we hope clarifies the situation with the data dictionary..

The intention of the dictionary is not to become the absolute list of all
tags within the xPL system, but rather to standardise those things where it
makes sense to do so..

Part of hammering this out has clarified an issue that's been hanging in
the
air somewhat: the presence of multiple switches, thermometers, etc within a
single gateway application or device.

Rather than having the situation of

TEMP1=
TEMP2=
TEMP3=

and so on, or even:

INDOORTEMP=
OUTDOORTEMP=

etc..

we have settled on the more elegant:

DEVICE=x
TEMP=

or

DEVICE=x
STATUS=

There are a lot of ways of saying "DEVICE=" (zone? area? room?
button?) but
they all basically mean the same thing, so, within the data dictionary, we
will be adopting "device=" as a method of specifying zones,
devices,
tribbles, buttons, switches, whatever... (we will also be looking at the
zonename concept, and probably en up with a single "label" tag
for labelling
sources, zones, whatever)

Hopefully, we have found the right balance between the freedom of simple
text, and the control you get from a tightly defined set of tags.

Keith, there are special cases we will hit in matrix systems where there
are
many to many relationships, and (if you don't mind) we'll use the
xPL->KAT5
switcher as a template for those sorts of systems, working out the best
ways
to address that environment.

Ian.