• From: Ihe Onwuka <ihe.onwuka@g...>
• To: "Costello, Roger L." <costello@m...>
• Date: Tue, 8 Apr 2014 21:17:39 +0100

On Tue, Apr 8, 2014 at 9:09 PM, Costello, Roger L. <costello@m...> wrote:
> Hi Folks,
>
> Suppose that you document the steps to be taken by an aircraft in its landing procedure:
>
> 1. Contact control tower
>
> 2. Enter glide slope
>
> 3. Correct for wind conditions
>
> Suppose those things must be followed in the sequence listed.
>
> The XML could be designed like this:
>
> <aircraft-approach-procedure>
>     <transition>Contact control tower</transition>
>     <transition>Enter glide slope</transition>
>     <transition>Correct for wind conditions</transition>
> </aircraft-approach-procedure>
>
> That design relies (implicitly) on the order of the <transition> elements for denoting the sequence of steps to be taken.
>
> An alternative design is to (explicitly) specify the order. Here is one way to accomplish this:
>
> <aircraft-approach-procedure>
>     <transition step="2">Enter glide slope</transition>
>     <transition step="3">Correct for wind conditions</transition>
>     <transition step="1">Contact control tower</transition>
> </aircraft-approach-procedure>
>
> Note that in this design it is not necessary to list the <transition> elements in a particular order since @step explicitly indicates the order.
>
> I vote for the latter as best practice. I invoke this principle as my justification:
>
>         Make implicit structures explicit.
>
> What do you think?
>

That script filling is an integral part of human cognition and I would
not advocate a specification practice that ignores that.

• References:
  • Make implicit structures explicit
    • From: "Costello, Roger L." <costello@m...>