Icarus Class: AttrRDBMetaphor
The mapping information to write the contents of an object attribute.
attrName Attribute may stay unnamed in attribute list.Attribute value must be specified.
  The name of the attribute which this mapping information has been written for.
type  Attribute has a default value. string
  Use one of the following values. integer int double real str string
  Type of the attribute. Supported types; int:0, double:3, str:5 (default).
column  
  Specify the rdb column where this attribute values to be written. Use this attribute, when you use schema and table attributes of the object metaphor.
locations Attribute is multivalued (list). MetaRDBLocation  
  List of rdb locations this attribute information should go.
link Attribute is multivalued (list). MetaRDBLocation  
  Rdb locations the attribute information should be linked by.
constraint  
  Column constraint definition
compositePK  Attribute has a default value. n
  Use one of the following values. no n yes y
  Shows whether this attribute is part of a composite primary key.