Data Type Descriptor Formats

This section describes the format of the TYPEDESC segment, which appears in records of type VARIABLE, SYSTEM_VARIABLE and HEAP_DATA. All of these record types come in three parts. First, the name or index number of the variable appears, which describes its identity; second, the type of the variable is described, such as array dimensions, data type, and whether it is a structure; finally, the data itself appears. This section describes how the data types are stored on disk.

The data types can be divided into several possible cases:

1. Scalar numbers, strings or pointers.
2. Array numbers, strings or pointers.
3. Structures.
4. Objects.

By convention, structures are always arrays, so the data type descriptors for arrays and structures naturally overlap. While objects can be stored in IDL save files, the CMSV library does not support them.