The new heroes are each unique with custom attributes and a set of different starting items / spells that give the player an edge in combat — or a vulnerability. (dualshockers.com)
Managers can create and manage groups based on flexible attributes such as team, sales region, hire date, or other custom attributes. (qaeducation.co.uk)
To facilitate interoperability of custom attributes across Reading Systems, vendors are strongly encouraged to document any extensions they implement in [Attribute Extensions]. (idpf.org)