Swallow Resource Centre
Swallow Family History - Hertfordshire, East London and Beyond
FGN EXPLAINED

In the pages of this website you will find reference to four digit numbers preceded with a lower case 's', for example:
 
               William SWALLOW (1827) [s1150]
 
The [s1150] represents the Family Group Number or FGN of the specific person or family.

This is a system devised by John Swallow (see below) for keeping track of families, generations and the links between them. This is very useful and works well within a paper system or a computer based system. It also ensures a discipline that helps validate data.

My own data is maintained within the Family Historian software programme, by creating custom attributes within the software these FGN numbers can be maintained and used as the basis of creating reports.

The theory is as follows: The FGN list consists of three columns headed Own, Child and Parent. At first entry into the database by an individual - say George Swallow - and where no other relationship is known, he would be allocated the next available family group number - FGN, say “s0836” (“s” is used for the Swallow base and other letters can be used for those researching other family trees).

If George then marries Mary, Mary is also allocated the same FGN in her Own column (her Parent column will always remain empty unless she is also a Swallow or a member of anther family tree you are researching). Now in the fullness of time George and Mary have children and each child in turn is allocated the same FGN into their Own and Parent columns (s0836). At this stage everyone person has the same FGN number and are tied together as a family group.

Now suppose one of George and Mary's the children - Charles - marries. Charles is allocated his Own FGN (the next available number in the sequence) - say "s0912" and this replaces the default number in his own column. His own Parent FGN never changes - it links him to George and Mary for ever. In addition, the previously empty Child column of George is now annotate with the new own number juts allocated to Charles - "s0912". It is important to remember that the Own and Parent columns can only ever contain one FGN. The Child column contains as many FGNs as children of the parents get married.

All this time the Parent column of George has been empty - if George's parent is located then his Parent FGN is to that of his Parent. If another child of George and Mary marries - say Robert - he will be allocated his own unique Own FGN number; this number will be added to that of the Child column of George, alongside that of Charles. The table below shows the allocations at this stage:

NameOwn ParentChild
George Swallow s0836 --- s0912, s0915
Charles Swallow s0912 s0836 ---
Robert Swallow s0915 s0836  


From a practical point of view the Child (or more correctly Children) column is only of interest if you are maintaining a non-computer based system as it is the only sensible way to point forward to an expanding family. In any computer based system - using a spreadsheet or a database then sort routines of any sort make locating generations a simple matter.

 

Temporary Numbers

Occasionally  you will see a number with a 't' prefix - t0041 - this indicates that it is a temporary number allocation pending the assigning of a correct FGN number. This is often  done when the included information if important but a final decision as of ownership has to be allocated using our central FGN register.

Occasionally you will also see an FGN number with a extra letter post-fixed - s0225y -. In such cases the parent of the now married is known and we waiting to allocate a new FGN to the new family unit.

Generally the reason for these 'blips' are administrative and just require a bit of time to sort out!

To see FGN's in action check out the FGN Index page.