Set here the properties of a crystallographic or atomic plane.
Reference
GAMGI can handle crystallographic planes, related with a cell containing 
the relevant crystallographic information, and atomic planes, defined by 
three non-colinear atoms.
To create crystallographic planes, set 
Reference to 
Cell.
GAMGI automatically shows a 
Cell entry, 
h, 
k, 
l 
entries to indicate the plane indices, plus a 
Vectors menu, to select 
the cell vectors to use, 
Conventional or 
Primitive. For the sake 
of simplicity, GAMGI does not accept 4-indice notation for planes or directions 
in hexagonal cells.
Pressing the mouse over a cell in the current layer, the cell identification 
is automatically written in the 
Cell entry. When a valid cell is found
and its 
Type is 
Projection, the default 
Polygon page 
is automatically replaced by a 
Projection page.
By default, only one family of crystallographic planes is created. 
To create a set of families simultaneously, press the button 
Set (TODO).
When 
Reference is set to 
Atoms, GAMGI automatically shows
three 
Atom entries. Pressing the mouse sucessively over three 
non-colinear atoms in the current layer, the three entries become occupied
and the plane defined. After pressing 
Ok, an error is shown if the 
atoms are disposed linearly.