GEDClean32 - What is GEDCOM

All genealogical database programs are designed to be able to share information in a common format. The GEDCOM specification defines a format that all such programs can create and understand.

GEDCOM is short for Genealogical Data Communication.

GEDCOM files contain only plain (ASCII) text. This means you can read them with any text editor or word processor (Notepad, Wordpad, or MS-Word, for example).

Each line of a GEDCOM file starts with a "level" number, which indicates whether the piece of data on that line starts a new record, or is part of the record above.

For example, a level "0" line might indicate the start of an "individual" record. The next line might be level "1", and contain the "name" of that individual:

0 @I2@ INDI
1 NAME John  /Doe/
1 SEX M

This is a section of the record about an individual with the first name "John", and last name "Doe". Reading this, we see that he is Male, and in this database the ID of his record is I2.

The true power of the GEDCOM format, however, is that it also contains the relationships between records. For example, further along in the file, we find something like this:

1 FAMS @F3@
1 FAMC @F1@

This says that this individual is a Spouse in family F3, and a Child in family F1.

Further along, we should expect to find a record that defines each of these families. Family records will contain information such as the IDs of the members of the family, and the date and place of the parents' marriage.

Armed with this basic information, you can now browse your GEDCOM file with confidence.

In a GEDCOM, all the information about an individual is together, but to find out about that individual's spouse, children or parents requires that you read the entire GEDCOM file into a database, to restore the pointers and links.

This is why GEDClean cannot, for example, know that an individual whose child was born 200 years ago is not likely to be still living. All GEDClean can know is what's in the INDI record.