>perl -MEncode -wle"for (0..255) { print if chr ne decode($ARGV[0], chr) }" iso-8859-1

>perl -MEncode -wle"for (0x20..0x7E,0x0A..0xFF) { print if chr ne decode($ARGV[0], chr) }" iso-8859-2
161
162
163
165
166
169
...