echo [ "string%dstring",<integer expression>]
The string <string> is echoed to the default output device as typed.
This command serves as a marker inside long macro files. It gives the
user a chance to include easy to find messages in order to follow
lengthy or nested structures.
The alternative command format allows to echo formatted strings to the
screen. Each "%d" is replaced by the value of the corresponding
parameter. The sequence of "%d" corresponds to the sequence of the
parameters. These parameters can consist of any integer expression.