Syntax
BD>lock : [-](S ) [, [-](S )] ...
where are belief storage numbers.
The LOCK: command is used to lock and unlock specified belief
storage areas. If the argument S is preceded by the symbol `-', the
belief store number S is `unlocked', otherwise it becomes `locked'.
When a belief store is locked, beliefs usually constructed via
BUILD: or COBUILD: commands are not constructed, and so
do not overwrite the values already present. It remains possible to
specify directly beliefs for locked storage areas. By default, all
belief storage areas are unlocked. The stores operand can be used
to obtain the total number of belief stores.
The LOCK: command is often used when we want to build two
alternative variance-covariance specifications for a collection of
quantities in stages, and also when we have output adjusted covariances
to a belief storage area which we want to be retained.
Beware that some controls force the unlocking of specified belief
stores. In particular, when the ac and scac controls
are used to direct adjusted covariance output from an adjustment or a
scan to a belief store, the given belief store is unlocked.