Various types of descriptive data have been placed in the margins since 1990, including historical data, biographical data, promotional markings, informational markings, and, most recently, web sites.

Historical data provides the public with a historical context for the issuance of the stamp.  Perhaps the most comprehensive treatment to date is the set of five World War II issues from 1991 through 1995 that provided text and maps that showed the major events in the war for each year.

1942 World War II 50^th anniversary issue.

Historical information on the war in Europe and Africa.

Biographical data concerning individuals began in February, 1990.  "Postmaster General Anthony M. Frank “started looking at the Great Americans series and he said, if a stamp doesn’t explain itself, if it leaves the customer saying ‘Why is this person on this stamp I’m buying?’ then the stamp design has failed.  And even if we made it possible for a window clerk to answer that question, Mr. Frank said, it wouldn’t help a person who received a letter with that stamp on it.  He’s not going to drive all the way down to his post office and ask a window clerk, and he’s not going down to the library and look it up.  Mr. Frank said to us:  You’ve got to fix it."  (Don McDowell, manager of the USPS Stamps Division, on why biographical material was being printed in the selvage, from Linn’s U.S. Stamp Yearbook 1990)  As a result, in February 18, 1990 the USPS printed biographical information (“Luis Munoz Marin (1998-1980.  First elected Governor of Puerto Rico, 1948.  Founder of Puerto Commonwealth.”) in the selvage of Scott 2173, the first stamp in the Great Americans series to contain such information.