diff --git a/doc/master/make_path_absolute b/doc/master/make_path_absolute
new file mode 100644
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+SYNOPSIS
+	string make_path_absolute(string str)
+
+DESCRIPTION
+	Absolutize a relative filename str given to the editor. Should
+	return the full pathname of the file to use. Any non-string
+	result will act as ``bad file name''.
+
+SEE ALSO
+	ed(E), valid_write(M)