[gurps] [VehicleML] Performance and Units

[Onno Meyer]

Gerald wrote:
> While Unit is great for generic, my point it is GURPS Vehicles and there 
> is only one unit that should be in <aspeed> so unit is redundant (but 
> should be in the DTD documentation which unit type should be in there.) 
> unit is only necessary if you want <aspeed> to also accept non mph.

Zan wrote:
> <speed medium="air" value="2360" units="miles/hour"/>
> <acceleration medium="air" direction="forward" value="2" units="g"/>
> <acceleration medium="air" direction="backward" value="6" units="g"/>
 
I think this goes to the core of what our VehicleML is 
good for. MathML has Presentation and Content variants 
to do both jobs.

GT Starships were my starting example because they are
relatively clear and uniform. Even so, separating unit 
and value makes problems. A volume of "10" with unit 
"ston" becomes "10 stons", while "1" and "ston" stays
"1 ston". But what about "-" and "stons"?

Of course we could elaborate, define rules to specify
that "ston" values other than "1" become "stons", and
that "cf" values other than "1" remain "cf". Doing 
that right is a major project. 

For Presentation VehicleML, I'm thinking of this right
now:

<performances>
  <gperformance>
    <speed>1,234</speed>
    <accel>12</accel>
    <decel>23</decel>
    <mr>1</mr>
    <sr>2</sr>
    <groundpressure>Low</groundpressure>
    <offroad>3/4</offroad>
  </gperformance>
  <wperformance>
    <speed>1,234</speed>
    <accel>12</accel>
    <decel>23</decel>
    <mr>1</mr>
    <sr>2</sr>
    <draft>4.5</draft>
    <flotation>123 tons</flotation>
  </wperformance>
  <aperformance>
    <comment>With loaded hardpoints</comment>
    <speed>1,234</speed>
    <accel>12</accel>
    <decel>23</decel>
    <mr>1</mr>
    <sr>2</sr>
    <stallspeed>123</stallspeed>
    <ceiling>12,345</ceiling>
  </aperformance>
  <sperformance>
    <accel>2 G loaded/3 G empty</accel>
    <mr>1</mr>
    <ftl name="Warpspeed">3 parsecs/day</ftl>
    <deltav>123 mps</deltav>
  </sperformance>
</performances>

Hard to use for calculations, easy to display. If there
is space performance, write "sAccel: " and add whatever
the value of "accel" is ...