OK, I think I get it. There is no good reason for rigidly ordering these elements, we've just run into a limitation of the XML Schema standard.

On Fri, Aug 1, 2008 at 6:55 AM, Ray Denenberg, Library of Congress <[log in to unmask]> wrote:
<cartographics> is defined as xsd:sequence because <scale> and  <projection>
are not repeatable, but <coordinates>  is repeatable.

<all> requires that each element occur zero or one time and would not allow
multiple <coordinates> elements.

<choice maxOccurs="unbounded"> (which MODS uses in cases without such
constraints)  would not constrain <scale> and <projection> to maximum one

(Contrast this for example with <subject> ........

<choice maxOccurs="unbounded">
<element name="topic"/>
<element name="geographic"/>
<element name="temporal"/>
<element name="titleInfo"/>




.....any of these subject categories may occur any number of times,
including zero, and the whole set may occur in any order.)

----- Original Message -----
From: "Joe Altimus" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, July 31, 2008 5:30 PM
Subject: [MODS] schema use of xsd:sequence to define children of the
cartographics element

I notice that the MODS schema uses xsd:sequence to define the children
of the cartographics element:

              <xsd:element name="scale" minOccurs="0" type="xsd:string"/>
              <xsd:element name="projection" minOccurs="0"
              <xsd:element name="coordinates" minOccurs="0"
maxOccurs="unbounded" type="xsd:string"/>

However, an example of <cartographics> in the MODS User Guidelines
does not conform to the schema:

   <coordinates>E 72--E 148/N 13--N 18</coordinates>
   <projection>Conic proj</projection>

so I wonder if the example is wrong or the Schema (xsd:all instead of
xsd:sequence)? Is there a strong reason why the children should occur
in a rigid order in this case?

Joe Altimus
Arizona State University Libraries