Modules

Here is a list of all modules:

Asynchronous Messaging	Structure for managing asynchronous state of CoAP resources
Block Transfer	API functions for handling PDUs using CoAP BLOCK options
Clock Handling	Default implementation of internal clock
DTLS Support	API functions for interfacing with DTLS libraries
DTLS Support (Internal)	Internal API functions for interfacing with DTLS libraries
Event API	API functions for event delivery from lower-layer library functions
Logging Support	API functions for logging support
Option Filters	API functions for access option filters
Pseudo Random Numbers	API functions for gerating pseudo random numbers
Rate Control	The transmission parameters for CoAP rate control ("Congestion Control" in stream-oriented protocols) are defined in https://tools.ietf.org/html/rfc7252#section-4.8
Resource observation	API functions for interfacing with the observe handling (RFC7641)
Sessions (Internal)	Structures, Enums and Functions that are not exposed to applications
String handling support	API functions for handling strings
Subscribe (Internal)	Structures, Enums and Functions that are not exposed to applications
URI Parsing Functions	CoAP PDUs contain normalized URIs with their path and query split into multiple segments