Why is a field sent to the server even though it's defined as canSave false?

[mathias]

I just noticed a thing i didn't remember a good answer for. :)

Say i have a .ds-field defined like this:

 
 <field name="locLat" type="float" title="loclat" required="false" hidden="true" valueXPath="location/lat" canSave="false"/>

I notice that if i have that field in a form, and save it, the field is still sent to the server. It would make sense to me if readonly-fields are not passed on to the server, i see it as spam data since i won't ever use it on add/edit. I suppose there's a reason for still sending it, but i could not come up with anything, perhaps besides logging? Thoughts appreciated.

[Isomorphic]

The field indicates the value the user saw when editing, which can be useful contextual information.

[mathias]

Well, as you can see the field is set to "hidden" so the user did not see it. I see what you mean though.