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No because by making Currency and Amount elements you are implying that they could potentially have substructures on their own.
Absent a schema prohibiting otherwise the content model for cost permits multiple Currency and Amount child elements. 

This may in fact be right because there could be an amount for each Currency but that then implies an immediate preceding sibling arrangement except that the content model of Cost doesn't prohibit the Amount preceding Currency - what then.

For all these reasons you eliminate the need for a schema to clarify all these questions by representing as 

<Cost currency="USD" amount="8.95"/>


On Thu, Sep 27, 2018 at 8:54 AM Costello, Roger L. <costello@mitre.org> wrote:

Hi Folks,

I hold this to be the fundamental axiom of XML:

          Make the structure of data explicit.

We accomplish that by adding a label (markup) to the data.

There are various terms for this notion of making the structure of data explicit: upconversion and uptranslation.

Elements with simple content and attributes are antithetical to the fundamental axiom of XML.

Here is an element with simple content and an attribute:

<Cost currency="USD">8.95</Cost>


The data USD is explicitly labeled. The label indicates that USD is a currency.

What about the data 8.95, is it labeled? No! It is anonymous/unlabeled. Note: Cost is not the label for 8.95; Cost is the label for the whole package.

In my most recent post, I asked, “What is that number (8.95)?” I received excellent responses: 8.95 is a price, 8.95 is an amount, etc. External knowledge was needed to label the data. The need for external knowledge completely contradicts the fundamental axiom of XML.

Therefore, don’t create XML like this:

<Cost currency="USD">8.95</Cost>

instead, create XML like this:



Do you agree?




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