This filter copies data along arbitrary direction (array 0, 1, 2). By default, Arraies are set along x, y, z-axes. You can edit the difference of locations of copied data with Periodic Boundary dialog. (suitable for non-cubic crystal data, for example).
This image shows a sigle particle at thr origin copied (3x3x3=27) times.
You can handle positions of copied data with expression.
See the documentation of Lua for the grammer of expression.
For example, shearing box can be achieved as follows.
|return true, nx, ny+nx*nt, nz|