1.   I have often suspected that by raking through the telephone directory according to a number code, you could extract a secret message.

2.   ISBN stands for International Standard Book Number, which is a unique number code assigned to books for the purposes of identification and inventory control.

3.   When Trithemius said that people can send messages without using letters he probably just meant they could use number codes instead.

4.   In some cases, worshippers punch in a number code that stands for a specific message.

5.   So a blood tester could have access to cells of fast horses, even though samples arrive at laboratories with number codes and not names.

6.   The jars are labeled only with a number code, police said.