MEGA Administration : Administrator Guide : Managing Data Writing Access : Customizing Writing Access Area Management : Calculated MetaAttribute
   
Calculated MetaAttribute
A calculated MetaAttribute is a software device enabling deduction of the MetaAttribute value of an object as a function of data around the object or dependent on other sources (system, current user, etc.).
MEGA uses a set of "conventional" MetaAttributes (including the writing access area) that do not require metamodel definition.
A substitution device is available in MEGA; it enables replacement of an implicit MetaAttribute by another for a MetaClass.
This device is required when you need to alter behavior of an existing MetaAttribute by implementing a calculated MetaAttribute.
To customize writing access area of an object, you must:
1. Create a MetaAttribute with characteristics close to those of the "_Authorization" MetaAttribute.
2. Substitute the "_HexaIdAbs" value of the new MetaAttribute by the "_HexaIdAbs" value of the "_Authorization" MetaAttribute.
3. Calculate the writing access area.