Here are the data structures with brief descriptions:

C_ldns_sha256_CTX
C_ldns_sha2_buffer_union
C_ldns_sha512_CTX
Cldns_dnssec_data_chain_struct
Cldns_dnssec_trust_tree_struct
Cldns_duration_struct
Cldns_radix_array_t	Radix node select edge array
Cldns_radix_node_t	A node in a radix tree
Cldns_radix_t	An entire radix tree
Cldns_rbnode_t	The rbnode_t struct definition
Cldns_rbtree_t	Definition for tree struct
Cldns_schwartzian_compare_struct	Structure to do a Schwartzian-like transformation, for instance when sorting
Cldns_sha1_ctx
Cldns_struct_buffer	Implementation of buffers to ease operations
Cldns_struct_dnssec_name
Cldns_struct_dnssec_rrs
Cldns_struct_dnssec_rrsets
Cldns_struct_dnssec_zone	Structure containing a dnssec zone
Cldns_struct_hdr	Header of a dns packet
Cldns_struct_key	General key structure, can contain all types of keys that are used in DNSSEC
Cldns_struct_key_list	Same as rr_list, but now for keys
Cldns_struct_lookup_table	A general purpose lookup table
Cldns_struct_output_format	Output format specifier
Cldns_struct_output_format_storage	Output format struct with additional data for flags that use them
Cldns_struct_pkt	DNS packet
Cldns_struct_rdf	Resource record data field
Cldns_struct_resolver	DNS stub resolver structure
Cldns_struct_rr	Resource Record
Cldns_struct_rr_descriptor	Contains all information about resource record types
Cldns_struct_rr_list	List or Set of Resource Records
Cldns_struct_zone	DNS Zone
Cldns_tsig_credentials_struct	Contains credentials for TSIG