Here are the data structures with brief descriptions:

Clis_api	LibInsane C API
Clis_device_descriptor	Basic informations regarding a scanner
Clis_dumb_read
Clis_item
Clis_log_callbacks
Clis_option_descriptor	Describes a scanner or source option and provides callback to read or change its value
Clis_scan_parameters	Describes what will be returned when scanning
Clis_scan_session
Clis_value	Variable
Clis_value_list
Clis_value_range