A typical structure file might look like this:

N KNbO3 tetragonal. Hewat (1973) J. Phys. C6, 2559-72

C 4.0000   4.0000   4.0660  90.0000  90.0000  90.0000

S GRUP P 4 m m

A K1     0.0000  0.0000  0.0230

A K2     0.0000  0.0000  1.0180

A NB2    0.5000  0.5000  0.5000

A O3     0.5000  0.5000  0.0440

A O4     0.5000  0.0000  0.5400

A O5     0.5000  0.5000  1.0400

T K1  5  1.04    1.04    1.26

T K2  5  1.04    1.04    1.26

T NB2 5  0.67    0.67    0.31

T O3  5  1.18    1.18    0.58

T O4  5  0.99    0.45    1.00

T O5  5  1.18    1.18    0.58

X NB-O 1.911,0,0,1

Expert commands might be: ct Si,1.2,0,0.7,0 nx2 tt p bo Si-O

This would change all Si atoms to radius of 1.2 and color 70% pure green (RGB). Two unit cells would be drawn along x, with semi-transparent (tt) polyhedrae (p) for all Si-O bonds.

 pt  perspective view*; pf  no perspective

 bt  black background*; bf white background

 at  axes*            ; af no axes

 ut  unit cell*       ; uf no cell

 dt  cell walls       ; df no cell walls*

 et  thermal ellipses ; ef spherical atoms* (not tested)

 st  smooth*          ; sf not smooth

 vt  very smooth      ; vf not very smooth*

 nt  atom names       ; nf no names*

 tt  transparent polys; tf solid polys*

 wt  wire frame       ; wf solid objects*

 s   small spheres*   ; r  radii of ions  ; i invisible

 l   line bonds       ; c  cylinder bonds ; n no bonds

 p   polyhedrae*      ; b  polys+lines    ; f polys+cyls

 nx2 double x-axis    ; ny3 and nz2 for multiple cells

 bmin 1.0 (min bond)  ; bmax 2.7 (max bond)

 A-O B-O              = A-O bonds (A-O,F means O or F)

 A1-O2 0,0.8,0        = A1-O2 bonds with A1 green (RGB)

 A1-A2 1.7,0,1,0      = valence Ro=1.7 (Acta.C.B41,244)+green

 ct A,1.9,0,1,0       = at A radius=1.9 color 0,0.7,0 (green)

 =someViewer          = use VRML viewer someViewer to display

 NOTE: last line of *.ccl file can be 'X list-of-commands'