It is very common for patients to be admitted under two different patient identification numbers by accident. Later on when this is discovered, many health information systems will allow an administrator to merge the duplicate records and then emit an HL7 patient merge message.

The general rule with merge messages is to allow the administrator of your system to handle merges manually. Your application should assist the administrator by providing all the relevant information, but should not handle merges automatically.

Table grammar design for merge messages is very simple. In most cases, a single flat table with the following fields will be sufficient:

The grammar root of this table should be the root of the message. By making use of Chameleon's ability to handle multiple configurations in one message definition file, it's then very straightforward to deal generically with all the different merge message implementations.