Change here object and crystallographic data for a single direction or a list
of directions.
To modify a direction, click over its graphic image, or write its identification
(name and number) on the 
Direction entry. To modify a list of directions,
press the button 
List (after creating the list of directions with
Direction->Select). Parameters for empty entries or 
Local choices
remain unchanged.
To change a direction name write the new name in the 
Direction entry,
followed by the direction number (GAMGI needs the number to identify the direction).
To change the name for a list of directions, press 
List first
and then write the new common name in the 
Name entry.
Reference
GAMGI can handle crystallographic directions (selecting 
Cell),
related with a cell containing the relevant crystallographic information,
and atomic directions (selecting 
Atoms), defined by two non-coincident
atoms.
For a single direction, 
Reference can be 
Cell,
Atoms or 
Local. For a list of directions, 
Reference
must be 
Local.
When 
Cell or 
Atoms is selected, the direction is recreated
from scratch (as if using 
Direction->Create) and its old content is
removed. As this requires local information for each direction, it cannot
be done for a lists of directions. When 
Local is selected, previous
features and contents are preserved, unless when specifically changed.
Cell
To create crystallographic directions, set 
Reference to 
Cell.
GAMGI automatically shows a 
Cell entry, plus 
u, 
v, 
w
entries to indicate the direction 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 
Line page
is automatically replaced by a 
Projection page.
By default, only one family of crystallographic directions is created.
To create a set of families simultaneously, press the button 
Set (TODO).
Atoms
When 
Reference is set to 
Atoms, GAMGI automatically shows
two 
Atom entries. Pressing the mouse sucessively over two
non-colinear atoms in the current layer, the two entries become occupied
and the direction defined. After pressing 
Ok, an error is shown 
if the atoms are coincident.