How to model a key/value multivalued property?

[franco_valente]

Hi,

I need to model a key/value "multivalued" property.I.e:
What I need is to tag contents by giving a weight to each tag, for example:

Psychology => 5
sport => 2
personal => 6

So, I can get my own taggable aspect by implementing this

<aspect name="l4a:TT1taggable">
   <title>Tassonomia TT-1</title>
   <parent>cm:classifiable</parent>
   <properties>
      <property name="l4a:TT1categories">
         <title>Categories</title>
         <type>d:category</type>
         <mandatory>false</mandatory>
         <multiple>true</multiple>
         <index enabled="true">
            <atomic>true</atomic>
            <stored>true</stored>
            <tokenised>true</tokenised>
         </index>
      </property> 
   </properties>
</aspect>
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But I want my "l4a:TT1categories" property to be a list of key/value items.
I know this kind of question is not specific for categories only. This is a  general modeling question.
How can I model this context? How do you suggest to continue?

[franco_valente]

Thanks Axel, now It's clear!
I'll try this way.

Francesco