Read-only Attributes in Template

[quant]

Could you please add the option for the attribute in the Template to be read-only?

Use:
I have templates (child) which are derived from another templates (parent). This derived templates have the same attributes as parent template (+ possibly some new ones), but certain attribute specifies the child template, so I want it to be read-only.

Example:

Template Car, attributes:
Type
Engine
Make
...

Derived Template, Van:
Type=Van (I want this to be read-only for all the Items that I derive from Van template)
Engine
...


This follows the same logic as is already used when you derive a Template from another Template, where the "Template Item" attribute becomes read-only one in the derived template.

Thanks!