Mike, The list of attributes for a contact can be found here: http://developer.constantcontact.com/doc/contactCollection#Contact
Support Engineer, Constant Contact
Is the list of attributes fixed or can I add my own ones when I create a contact?
E.g. can I add the following attributes to a contact: Age: 30, Status: single, etc?
If yes, can I create a campaign targeted at contacts that have some specific attribute values e.g. Age:24 and Status: Married?
The list of attributes is fixed, but we do have 15 available 'Custom Fields' that you can use to store whatever field of information you want that we do not already have. For more information on custom fields please view Contact Detail and Custom Fields. Please be aware that each custom field can store up to 50 characters of information per field.
I hope this answers your question. If you have any others please let us know. Thanks.