Before we start pressing buttons, a word on the style that we have
adopted. Each [B/D] command line consists of a command followed by a
list of arguments to the command. The case (upper or lower) that you use
is not important: the text that you input is generally converted
internally to lower case, with some minor exceptions to handle headings
of output and similar titling. The command must be separated from its
arguments by at least one space, or by one colon. The letters forming
the name of a command must be contiguous, although you can intersperse
spaces freely in the argument list. Each line is terminated by a
carriage return which we indicate with the 
symbol.
We are going to use a bold typeface to show the text
that you should type at the computer keyboard, and we will usually
preface this text with a prompt (such as BD>) which you should
not reproduce. Remember to complete each line with a carriage return.
As an example, we will issue the command that terminates the program. This is the STOP: command, which is our usual way of ending a [B/D] session. Try it now by typing the command below, and then restart the program.
BD>stop: 
When the program has restarted, enter the following command:
BD>keep:log=mylog
This asks [B/D] to maintain a record of the results output during the session in the file called ``mylog'' in your current directory. (Any file of the same name that already exists there will be overwritten.) You may choose a file name other than ``mylog'' (subject to the file-naming convention for your computer) if you wish.