The UniqueID is designed to track individuals unambiguously as family trees are transferred from one application to another. Whenever a new individual is created in a compatible app, the app generates a 16-byte unique identifier that stays with that record as it is exported and imported between different apps.
UniqueIDs were first used within Personal Ancestral File, but have now been adopted by many other (but not all) apps. Despite being developed by FamilySearch, they were not included in either GEDCOM 5.5 or 5.5.1, but are part of the GEDCOM-L extension.
GEDCOM-L recommended that UniqueIDs are represented in GEDCOM files by a 32-character hexadecimal string (0 to 9 and A to F), followed by a 2-byte/4-character checksum. The checksum is calculated from the main string value, and serves to identify any errors of transcription. This 36-character string is the form originally introduced by Personal Ancestral File, and later adopted by other apps.
GEDCOM 7.0 kept the same basic calculation method for the UniqueID, but recommended a hyphenated format with no checksum (which is rarely required, as UniqueIDs are generally read and transferred by computer, not entered manually by users).
This mixed history has resulted in different apps implementing different, and sometimes incompatible, forms of the UniqueID, limiting portability. For example, if a UniqueID is generated in Family Historian and exported to RootsMagic 8, the hyphens are removed and a checksum added, so the two are no longer equivalent.
It is much better to convert UniqueIDs in Family Historian to the format used by the receiving application prior to export.
This plugin makes these format conversions (which are fully reversible), enabling Family Historian UniqueIDs to be exported into any compatible application and reimported in unchanged form.
The following compilation of currently available applications summaries how each handles UniqueIDs. Please raise any additions or corrections on the FHUG Forum, so the list can be kept up to date.
Listed formats are:
- 32 character, hyphenated, no checksum (GEDCOM 7.0 preferred format).
- As 1, but not hyphenated.
- As 2, but with a 4 character checksum (GEDCOM-L preferred format).
Family Historian (Version 7.0.8 onwards)
- Generates in format 1
- Imports all formats and keeps imported value unchanged
RootsMagic 7
- Generates in format 3
- Discards format 1, converts format 2 to format 3
RootsMagic 8
- Generates in format 3
- Imports all formats, and converts to format 3
Legacy 9
- Generates in format 3
- Converts format 1 to format 3, discards format 2
MyHeritage Family Tree Builder
- Generates in format 2
- Imports all formats and keeps imported value unchanged
My Family Tree
- Does not support UniqueID in GEDCOM 5.5.1 mode
- Generates in format 1 in GEDCOM 7 mode, but does not import _UID tags, only the GEDCOM 7 form of UID.
Plugin Format UniqueID
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