Curiosity Corner #195: a legitimate excuse to keep the selvedge

Mourning stamps, generally, are characterised by their colour
black or purple, and, in the most part, by the inclusion of a black
border around the stamp.

In this emancipation commemorative, converted to a memorial,
an inscription was added to each stamp, but the black stamp border
was relegated to the selvedge on the sheet.
(not shown, as I don't have it

http://cjoint.com/data/irgFsBv1b5.htm

Source: David Plummer 1983 "A Sombre Theme"