Architecting and designing : Data modeling : Components of an entity relation diagram : Objects in an ERD : Data element
  
Data element
The data element definition specifies the characteristics that apply to all instance of the data, regardless of what model or entity it is used in:
data type
type qualifiers: length, precision
default value
check constraints
data owner
domain.
The physical characteristics of any data element are always inherited by all attributes derived from that data element. Therefore, any change made to a data element affects all objects derived from that data element. In addition, any change to any attribute automatically changes the data element on which it is based, and, therefore, all other attributes based on that data element. If you delete a data element definition, all attributes that are instances of the deleted data element, and all references to the deleted attributes in all models within the encyclopedia, are deleted.
See also
Objects in an ERD