XBee Firmware Library  1.6.0
Here is a list of all modules:
[detail level 1234]
 1-Wire components
 DS18B20 digital thermometer
 DS1904 Real-Time Clock
 1-Wire driver
 Analog Digital Converter (ADC)
 CPU Drivers
 Low-Voltage Detection (LVD)
 Power Management (PM)
 Capacitive Board (I2C)
 Character LCD
 24xxx EEPROM
 25AAxxxx/25LCxxxx EEPROM
 Virtual EEPROM
 General Purpose Input/Output (GPIO)
 Interrupt ReQuest Control (IRQ)
 Standard GPIO
 Hardware Abstraction Layer (HAL)
 Freescale/Codewarrior (Programmable XBee)
 Rabbit/Dynamic C
 High Resolution Timer
 Input Capture component
 Inter-Integrated Circuit (I2C)
 LCD Display (SPI)
 Miscellaneous functions
 Output Compare component
 Pulse-Width Modulation (PWM)
 Real Time Clock (RTC)
 Serial Peripheral Interface (SPI)
 Universal Asynchronous Receiver-Transmitter (UART)
 Utility/Support Code
 Byte-swapping functions
 Circular Buffer
 XMODEM code used by the firmware update process
 Wireless Personal Area Networking (WPAN)
 Cluster/Endpoint layer
 Datatypes and support functions
 XBee Interface
 AT Commands
 AT Mode
 Device Interface
 Digi Data Endpoint
 Over-The-Air Firmware Update Cluster
 Transparent Serial Cluster
 Firmware Updates
 Glue layer between XBee Device driver and WPAN
 Node Discovery
 Serial Interface
 XBee-specific support of ZCL Commissioning
 ZigBee Networking
 ZigBee Cluster Library
 64-bit integer support
 Cluster Client support code
 Attribute Reporting (incomplete)
 Basic Cluster
 Commissioning Cluster
 Identify Cluster
 On/Off Cluster
 Time Cluster
 ZigBee Data Object/ZigBee Device Profile