+# commas or dashes. Whitespace may appear after commas.
+#
+# Environment variables:
+#
+# 1. If UPDATE_COPYRIGHT_FORCE=1, a recognized FSF copyright statement
+# is reformatted even if it does not need updating for the new
+# year. If unset or set to 0, only updated FSF copyright
+# statements are reformatted.
+# 2. If UPDATE_COPYRIGHT_USE_INTERVALS=1, every series of consecutive
+# copyright years (such as 90, 1991, 1992-2007, 2008) in a
+# reformatted FSF copyright statement is collapsed to a single
+# interval (such as 1990-2008). If unset or set to 0, all existing
+# copyright year intervals in a reformatted FSF copyright statement
+# are expanded instead.
+# 3. For testing purposes, you can set the assumed current year in
+# UPDATE_COPYRIGHT_YEAR.
+# 4. The default maximum line length for a copyright line is 72.
+# Set UPDATE_COPYRIGHT_MAX_LINE_LENGTH to use a different length.