Here are the data structures with brief descriptions:

Caz_context	A context is a node within a tree that represents expiration times and key/value pairs
Caz_http_policy_retry_options	Allows you to customize the retry policy used by SDK clients whenever they perform an I/O operation
Caz_http_request	Structure used to represent an HTTP request. It contains an HTTP method, URL, headers and body. It also contains another utility variables
Caz_http_response	Allows you to parse an HTTP response's status line, headers, and body
Caz_http_response_status_line	Represents the result of making an HTTP request. An application obtains this initialized structure by calling az_http_response_get_status_line()
Caz_iot_hub_client	Azure IoT Hub Client
Caz_iot_hub_client_c2d_request	The Cloud-To-Device Request
Caz_iot_hub_client_method_request	A method request received from IoT Hub
Caz_iot_hub_client_options	Azure IoT Hub Client options
Caz_iot_hub_client_twin_response	Twin response
Caz_iot_message_properties	Telemetry or C2D properties
Caz_iot_provisioning_client	Azure IoT Provisioning Client
Caz_iot_provisioning_client_options	Azure IoT Provisioning Client options
Caz_iot_provisioning_client_register_response	Register or query operation response
Caz_iot_provisioning_client_registration_state	The registration operation state
Caz_json_reader	Returns the JSON tokens contained within a JSON buffer, one at a time
Caz_json_reader_options	Allows the user to define custom behavior when reading JSON using the az_json_reader
Caz_json_token	Represents a JSON token. The kind field indicates the type of the JSON token and the slice represents the portion of the JSON payload that points to the token value
Caz_json_writer	Provides forward-only, non-cached writing of UTF-8 encoded JSON text into the provided buffer
Caz_json_writer_options	Allows the user to define custom behavior when writing JSON using the az_json_writer
Caz_span	Represents a "view" over a byte buffer that represents a contiguous region of memory. It contains a pointer to the start of the byte buffer and the buffer's size
Caz_span_allocator_context	Defines a container of required and user-defined fields that provide the necessary information and parameters for the implementation of the az_span_allocator_fn callback
Caz_storage_blobs_blob_client	Azure Storage Blobs Blob Client
Caz_storage_blobs_blob_client_options	Allows customization of the blob client
Caz_storage_blobs_blob_upload_options	Allows customization of the upload operation