An expression that resolves to the contents of the I-descriptor.
Description
The ITYPE function returns the contents of the compiled I-descriptor. You can read the I-descriptor from a file dictionary into the itype variable, then use the ITYPE function to return its contents.
An I-descriptor can reference a record ID (@ID) or a field value in a data record @RECORD). For further details, refer to the list of System Variables.
An invalid value for itype generates a <SUBSCRIPT> error.
