IDL supports integers, real and string data types, with varying degrees of precision for integer and real types. Four Boolean operators are provided (not, and, or and xor).
Arrays of any IDL data type can be created, and all elements of an array must of the same type. As in Fortran, IDL arrays are indexed in a row-major format (i.e., specify row then column when identifying an element). More complex structures can also be created, however. These structures are collections of scalars, arrays or other structures contained within a variable, and so are particularly useful for importing data.
Scientific Data Formats
IDL supports the following scientific data formats:
CDF - Common Data Format (2.5)
HDF - Hierarchical Data Format (4.0)
NetCDF - Network Common Data Format (2.4)
A full set of routines for reading, creating and handling these formats is supplied and documented in a separate manual, Scientific Data Formats.