A method executed at a client computer accesses a data record having a fixed set of predefined fields and a set of custom fields. Each predefined field has a predefined field name and a field value, and each custom field has a user-specified field name and a field value. The method displays the data record in a graphical user interface, which includes data entry controls for user specification of a field name and a field value. The method receives input from a user that includes a user-specified field name in the data entry controls. When the user-specified field name matches a field name of a predefined field, the method stores a user-supplied value in that predefined field. When the user-specified field name does not match the field name of any predefined field, the method stores the user-specified field name and the user-supplied value in an allocated custom field.