title: Limit PUT acces to a property within an asset
body: <p>Instead of giving full update access to a participant I'd like to give him update access to a specific property within the asset.</p>
  
  <p>From what I've read from the documentation it's possible to apply a rule to a property.</p>
  
  <p><strong>Rule</strong>:</p>
  
  <pre><code>rule PatientAddMentor {
      description: "A patient is allowed to add mentors"
      participant(p): "nl.epd.blockchain.Patient"
      operation: UPDATE
      resource(m): "nl.epd.blockchain.MedicalFile.mentors"
      condition: (m.owner.getIdentifier() == p.getIdentifier())
      action: ALLOW
  }
  </code></pre>
  
  <p>The part where I am stuck at is how to target the asset in the condition.  I'm assuming (m) equals the mentors in the condition because the error message says that the participant does not have UPDATE rights. (I'm not sure if it's even possible.)</p>
  
  <p><strong>Model:</strong></p>
  
  <pre><code>namespace nl.epd.blockchain
  
  asset MedicalFile identified by bsn {
    o String                    bsn
    --&gt; Patient                 owner
    --&gt; Patient[]               mentors optional
    --&gt; Organisation[]          organisations optional
    o Visit[]                   visits optional
    o String[]                  allergies optional
    o Treatment[]               treatments optional
    o Medicine[]                medicine optional
  }
  
  participant Patient identified by bsn {
    o String bsn
    o String firstName
    o String namePrefix optional
    o String lastName
    o String email
    o String telephoneNumber
    o String birthday
    o String gender
    o String city
    o String zipCode
    o String street
    o String houseNumber
    o String houseNumberExtra optional
  }
  </code></pre>