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XMM-Newton Science Analysis System


deceit (deceit-1.18.2) [xmmsas_20050815_1803-6.5.0]

Meta Index / Home Page / Description / Detailed syntax

dataset

A deceit template comprises zero or more dataset specifications. The dataset specifications are placed into a file, and cannot appear in the body of any other specification. There is no limit to the number of dataset specifications which may appear in a template, but within a template each dataset name must be unique.

The general form of a dataset specification is as follows:

         dataset dataset-name optional-expresion
         < 
                  ... dataset item specifications ...
         >

where,

• dataset is the dataset specification keyword. This keyword is used to begin a new dataset specification.

• dataset-name is the name of the dataset. There must be no other dataset specifications with the same name in the template. It has type string-expression (which may be a literal string). If the file exists it will be overwritten.

• optional-expression is an optional expression which is evaluated after the last item in the body has been evaluated.

The header part of the dataset specification (i.e., dataset dataset-name optional-expression) must be placed onto a single line. The subsequent dataset body, which is delimited by $<$ and $>$, is optional but, if present, must begin on a new line. This is due to a limitation of the deceit interpreter.

The body of the dataset specification comprises zero or more of the following specifications:

• table

• array

• attribute

• history

• comment

Any number of these items may appear in a dataset specification.

The variable dat is a predefined variable, the value of which is a pointer to the dataset being created, and may be referenced in the optional expression, and also in the expressions of the dataset item specifications. For example,

       dataset "set" verifyDataset(dat) 
       < 
       ...
       >

where verifyDataset might be a user-defined function (see 3.3) that takes a pointer to a dataset and, say, checks that the dataset conforms to some standard. The function is executed when the interpreter reaches the end of the dataset specification block.