Here is a list of all files with brief descriptions:

[detail level 1234]

docs
include
rclc
detail
cdr.h	CDR serialization helpers
nros_generated.h
serialization_format.h	RFC-0088 D5 — the linked backend's serialization format, as a compile-time fact the C API can assert on
action.h	Action server and client API
check.h	Error-check convenience macros for the nros C API
client.h	Service client API
executor.h	Callback executor (polling) API
init.h	<rclc/init.h> at upstream's include path (phase-492 W2, phase-501)
log.h	Phase 88.12 — ROS 2 style leveled logging surface for the C API
node.h	<rclc/node.h> at upstream's include path (phase-492 W2, phase-501)
publisher.h	Topic publisher API
rclc.h	Umbrella header for the nano-ros C API, at upstream's path
service.h	Service server API
subscription.h	Topic subscription API
timer.h	Periodic timer API
types.h	Shared types and constants for the nros C API
visibility_control.h
rclc_lifecycle
rclc_lifecycle.h	<rclc_lifecycle/rclc_lifecycle.h> at upstream's include path (phase-492 W2, RFC-0089)
rclc_parameter
rclc_parameter.h	The C parameter server: rclc's API over the executor's store