Current and previous adjustments

Regarding adjustments, at any point the program may be in one of the following states. By an adjustment we mean the adjustment of some collection B by another D, and all the results pertaining to the adjustment - adjusted expectations, variances, resolution matrices, and so forth.

state 1

There is no adjustment defined.

state 2

The base to be adjusted is prepared for adjustment, but there is no adjustment as yet.

state 3

There is one single simple adjustment which we call the current adjustment.

state 4

A partial adjustment has been carried out following a simple adjustment. The overall adjustment is termed the current adjustment; the former adjustment is termed the previous adjustment; and results concerning the difference between the two (i.e. the partial adjustment) are available.

state 5

An iterative adjustment has been carried out. Under these circumstances, the current adjustment is not defined as these two kinds of adjustment are incompatible. See §9.3 for further details. A former iterative adjustment is cleared by an ADJUST:  command.