Modules
Here is a list of all modules:

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
Asynchronous Messaging | Structure for managing asynchronous state of CoAP resources
Block Transfer |
Clock Handling | Default implementation of internal clock
Option Filters |
Pseudo Random Numbers |
Resource observation |
URI Parsing Functions | CoAP PDUs contain normalized URIs with their path and query split into multiple segments