# Association Pool¶

Association pools are simply tables. Pools are instantiated using the AssociationPool. This class is simply a subclass of astropy Table. As such, any file that is supported by astropy I/O can be used as an association pool.

Each row of a pool defines a member, and the columns define the attributes of that member. It is these attributes that the generator uses to determine which members go into which associations.

Regardless of any implied or explicit typing of data by a table file, internally all data are converted to lowercase strings. It is left up to the individual association definitions on how they will use these attributes.

For JWST Level2/Level3 associations, there is a special case. If an attribute has a value that is equivalent to a Python list:

[element, ...]


the list will be expanded by the Level2/Level3 associations. This expansion is explained in Member Attributes that are Lists