Actually, Fred, not all genealogists use primary, secondary and tertiary in reference to sources. In fact mosts genealogists I know use the following distinctions:
A Source is either original or derivative. It's either the original marriage certificate, made at the time of the marriage, or it's a copy or a transcription-- i.e., derivative. For example, if I was to use the California Death Index as the source for my grandmother's death date and place, that would be a seconday source. Her death certificate made at the timie of her death is an original source.
The Information in a source is either primary or secondary. Primary information is provided by someone who was there at the event. The information I provided on my marriage license is primary. The information about a deceased person's birth date on his death certificate is secondary if provided by an informant who was not present at the birth. (i.e., the son or daughter of the deceased).
The Evidence suggested by the information in the source is either direct or indirect. It either directly answers the research question or it indirectly answers the research question. The date on my grandmother's birth certificate provides direct evidence of her birth; her age in the 1910 census provides indirect evidence of her birth.
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