Variables
DataSet supports variables of the following types: Note that Char is not supported.

If you try to create a variable of a type that is not listed in the list, the exception InvalidOperationException occurs. The static method DataSet.IsSupported(Type) makes a dynamic check to determine whether a type is supported.

Metadata
Variable metadata is a dictionary of keys and values and is represented by the class MetadataDictionary.

A key is a string of 256 characters or less. A metadata key cannot be null or an empty string and cannot contain the following Unicode symbols: '/', '0x00'-'0x1F', '0x7F'-'0xFF'.

A value is an instance of any supported type or a one-dimensional array of such a type.