hy_datum_list: Extract datum list from HYDAT database
Description
DATUM look-up Table
Usage
hy_datum_list(hydat_path = NULL)
Arguments
hydat_path
The path to the hydat database or NULL to use the default location
used by download_hydat. It is also possible to pass in an existing
src_sqlite such that the database only needs to be opened once per
user-level call.