# Shift limits

Imposing meaningful shift limits is an important part of the design of a projects.

The shift limiting policy is governed by two parameters: the extent of the allowed limit itself (`area_search` or `lim`), and the *way* the limits are imposed (i.e., from which position in the data particle) is controled by ` area_search_modus` or `limm`:

- 0: no shift limiting policy
- 1: shifts limits are imposed from the center of the box
- 2: shifts limits are imposed from the putative position of the particle as computed by a previous iteration.

## In the dcp GUI

The both parameters that concern shifts can be found in the Numerical Parameters panel in the Wizard.

## From the command line

Limits are defined separately for each round, so that you need to append '_rX' (X is the number that identifies the round) to select the round where you operate the parameter change.

For instance, to change the extent of the limits on the first round of project ` myProject`, you'd write in Matlab (or the standalone console):

` dvput myProject -area_search_r1 [4,8,8] `

or equivalently:

` dvput myProject -lim_r1 [4,4,4] `

The modus can be changed with `area_search_modus` or `limm`, for instance:

` dvput myProject -area_search_modus_r1 1 `

or equivalently:

` dvput myProject -lim_r1 1 `