Question
What is a GUID (Global Unique Identifier), and why would I need to use one? Why is this a better unique identifier than the entry-Id?

Answer
A GUID, or Global Unique Identifier is a 30-character unique string. To create one, reference KB entry 11650. This KB discusses the why, not the how.

A unique string is indispensable when creating parent-child relationships, or any other 1-to-many or many-to-many relationship. Before the advent of GUID's such relationships were bound together using an entry-Id. This was sufficient, but had the following two weak points:

1) An entry-Id does not exist at create time. When a user is submitting an entry, they may want to define the child entries before hitting submit, but the entry-Id does not exist until after the user has hit submit.

2) An entry-Id is only unique on a per-form and per-server basis. The entry Id may be duplicated in other forms, or the same form on another server. Also, in the event of a hardware failure where lost data is eventually restored from backup, duplicate entry-Id's may have occurred during the outage that conflict with the restored data.

A GUID is unique globally. The data can move to other forms on other servers at other companies in other parts of the world, and the mappings that are defined by the GUID's will remain true.

The length of the GUID as generated by the Application-Generate-GUID command is 30 characters and will be a combination of upper and lower case letters as well as numbers.

The 30-character GUID is composed of:

- 2 char prefix, padded with underscore if necessary
(default prefix is "ID" if no prefix is supplied)
- 12 char server MAC address, truncated or padded with zeros on the left as necessary.
- 8 char datetime (seconds, hex, since start of 1 Jan 1970)
- 8 char clock ticks (hex, since start of server, with rollover)
returns 30 char GUID + 1 char string termination.
or NULL on error;

Note: This is subject to change between releases.