PUNCH <File name> {MAP | DSN6 | HKL | PACKED | ATOMx} -
[{SOURCE <Id> | CORRECT <Id> | -
ADD <Id1> <Id2> | SUBTRACT <Id1> <Id2> | -
MULTIPLY <Id1> <Id2> | DIVIDE <Id1> <Id2> |
PATTERSON <Id>}] -
[HIGHEST <Value> ] -
[BLUR <Value>] [SCALE <Value>] -
[{GRID 3<Value> | OVERSAMPLE <Value>}] -
[{LAYOUT 6<Value> | ASYMMETRIC}]
One may PUNCH data in the formats:
The rest of the PUNCH command line describes the origin of the information
and the details of the file to be produced. The various modifiers (SCALE,
BLUR, etc.) are described in the ``Standard TNT Data Statements'' section
(page 
).
The default coefficient file is an asymmetric unit of coefficients calculated from the atomic positions.
The default map is a molecular volume of model electron density written in Ten Eyck map format, sampled at a rate proper for representing such a density function.
What kind of map?
There are five types of sources for the information in a file. If no source is explicitly mentioned the program uses the atomic coordinates for the source. This is how model electron density and model structure factors are produced.
The second type of source is introduced via the SOURCE keyword. This keyword is followed by the file identifier of a map or coefficient file which is processed to produce the new file. If the data type of the input file differs from that of the output file the proper data type conversion is performed.
The CORRECT keyword is the third type. It behaves just like the SOURCE keyword except that the coefficients read, or calculated from, the file are moved to the correct asymmetric unit and sorted. Usually this operation is only required when a data set of observed reflections are being converted to a TNT format. In such a case you would read the illegal HKL file with the CORRECT keyword and write out a new HKL file. One could read a map file with the CORRECT keyword but that would be wasteful, the code which converts the map to structure factors will automatically produce data in the correct asymmetric unit and sorted in the proper order.
CORRECT also restricts the asymmetric unit of the data to include only unique reflections. All other types of sources in TNT will produce a small number of redundant reflections.
The fourth type of input is controlled with the ADD, SUBTRACT, MULTIPLY, and DIVIDE keywords. These keywords are followed by two file identifiers. The data in these two files are read and each transformed to the output data type. Then the contents are combined using the specified operator and written to the file.
One must use these keywords with care. It is quite likely that the operation you request will change either the space group, the resolution limit of the data, or both.
The last type of ``source" is controlled by the PATTERSON keyword. This keyword indicates that the data to be written will be either Patterson coefficients or a Patterson map, depending upon the output file's format.
How much map to write?
While the default map layout is a molecular volume this can be overridden. With the keyword ASYMMETRIC one can request an asymmetric unit of density. A more specific request can be made using the LAYOUT keyword.
These keywords are meaningless when writing Fourier coefficients.
How large will the map file be?
When writing a map the program will choose a sampling rate, the grid, for the map. The sampling rate is chosen based on the highest resolution Fourier component of the map. While this is simple when the map is to be calculated from Fourier coefficients it is another matter when calculating density from atomic coordinates. In this case the map will have to be sampled very finely because the atoms contain such high resolution data. One can reduce the size of the map by blurring out the high resolution terms you are not interested in. This is done with the BLUR option. When you use the BLUR option you must remember to indicate to the program reading the map that it has been blurred, because the map must be sharpened when read.
Fourier will never write a map with a non-zero blur unless you specifically
request it. It is usually wise, when writing calculated electron density
maps to blur them with a value of 20Å 
.