Indicated the type of data that can be stored in a structured data
entity (e.g. a table).
If
[type_code][google.cloud.automl.v1beta1.DataType.type_code]
== ARRAY, then
list_element_type is the type of the elements.
If
[type_code][google.cloud.automl.v1beta1.DataType.type_code]
== TIMESTAMP
then time_format provides the format in which that time
field is expressed. The time_format must either be one of: *
UNIX_SECONDS * UNIX_MILLISECONDS *
UNIX_MICROSECONDS * UNIX_NANOSECONDS (for
respectively number of seconds, milliseconds, microseconds and
nanoseconds since start of the Unix epoch); or be written in
strftime syntax. If time_format is not set, then the
default format as described on the type_code is used.
If true, this DataType can also be NULL. In .CSV files
NULL value is expressed as an empty string.
