Typographical Conventions

The following typographical conventions are used throughout the IDL documentation set:

UPPER CASE type
IDL functions and procedures, and their keywords are displayed in UPPER CASE type. For example, the calling sequence for an IDL procedure looks like this:

   CONTOUR, Z [, X, Y]

Mixed Case type
IDL object class and method names are displayed in Mixed Case type. For example, the calling sequence to create an object and call a method looks like this:

   object = OBJ_NEW('IDLgrPlot')  
   object -> GetProperty, ALL=properties

Italic type
Arguments to IDL procedures and functions — data or variables you must provide — are displayed in italic type. In the above example, Z, X, and Y are all arguments.

Square brackets ( [ ] )
Square brackets used in calling sequences indicate that the enclosed arguments are optional. Do not type the brackets. In the above CONTOUR example, X and Y are optional arguments. Square brackets are also used to specify array elements.

Courier type

In examples or program listings, things that you must enter at the command line or in a file are displayed in courier type. Results or data that IDL displays on your computer screen are also shown in courier type. An example might direct you to enter the following at the IDL command prompt:

   array = INDGEN(5)  
   PRINT, array

In this case, the results are shown like this:

      0       1       2       3       4