Most of [B/D]'s output is controlled by the output options described in this chapter. Output options can be handled in two separate ways. Firstly the OPTION: command can be used to toggle an output option on or off, and the setting of the option remains in force until it is explicitly altered by a subsequent OPTION: command. We might use this way of setting an output option if we are interested in seeing the same output for (for example) repeated adjustments.
Secondly, the SHOW: command can be used to access the same output directly and temporarily. We might use this method to view the results of one adjustment before proceeding to other aspects of an analysis. Note that the temporary use of an option within a SHOW: command cannot affect the usual setting of the option.
Initially, all output options are switched off by default. A list of output options is available interactively by issuing a LOOK: command with argument options .
Many options come in standard, extended, and standardised form, such as the cd , cd+ , and cd* options. We tend to use the `+' suffix to mean that the output will be more detailed than for the standard option; and the `*' suffix for standardised output. The latter tend to be concerned with linear combinations of quantities, and the standardisation usually means that the linear combinations are output with coefficients for quantities standardised to have expectation zero and variance unity.