troubles designing schema

Hi,

I have an XML document that has elements in it that have the
same tagname, but different mandatory values for the
attributes. I am having one heck of a time trying to design
a schema for these types of documents.

An example of the type of xml I am trying to develop a
schema for is below:

<moby:BasicGFFSequenceFeature>
    <moby:multi_key_value_pair
moby:articleName="column9_tag_value" moby:id=""
moby:namespace="">
        <moby:String moby:articleName="value" moby:id=""
moby:namespace=""/>
        <moby:String moby:articleName="key" moby:id=""
moby:namespace=""/>
    </moby:multi_key_value_pair>
    <moby:String moby:articleName="reference" moby:id=""
moby:namespace=""/>
    <moby:String moby:articleName="source" moby:id=""
moby:namespace=""/>
    <moby:String moby:articleName="method" moby:id=""
moby:namespace=""/>
    <moby:Integer moby:articleName="start" moby:id=""
moby:namespace=""/>
    <moby:Integer moby:articleName="stop" moby:id=""
moby:namespace=""/>
    <moby:Float moby:articleName="score" moby:id=""
moby:namespace=""/>
    <moby:String moby:articleName="strand" moby:id=""
moby:namespace=""/>
    <moby:String moby:articleName="frame" moby:id=""
moby:namespace=""/>
    <moby:String moby:articleName="phase" moby:id=""
moby:namespace=""/>
</moby:BasicGFFSequenceFeature>

As you can see, the tagname is repetitive, but the
articleNames, which are fixed, are different. Moreover, the
number of elements is important as well, so you would always
see all of the elements together or not at all.

Can this be done? If so, how? What am I missing?

Thanks way in advance for any insight.

Eddie Kawas