The APIs listed in this section provide ANSI-C interfaces.

All Error Codes - Complete list of error codes returned in TReK.
CFDP API - Allows reliable transfer of files over unreliable links using the CCSDS File Delivery Protocol.
Command ANSI-C API - Provides backward compatibility with the Release 3 TReK Command API.
Device Services API - Provides functions to send and receive data over various devices including TCP and UDP sockets.
Email and Text API - Provides interface to send email and text.
HPEG API - Provides information from the HOSC to Payload Ethernet Gateway (HPEG).
IONizer API - Provides functions to monitor an Interplanetary Overlay Network (ION) node.
Record API - Provides functions to create, populate, and close record files.
Telemetry ANSI-C API - Provides backward compatibility with the Release 3 TReK Telemetry API.

Supported Compilers
TReK code was created with the following compiler versions.

Operating System	Compiler Version
RHEL 8.x	gcc/g++ 8.5.0
Windows 10	Visual Studio 2012
Windows 10	Visual Studio 2015
Windows 10	Visual Studio 2017

Environment Variables
The TReK installation will create environment variables that can be useful for your project files. The table below list each environment variable and notes if it is provided on each operating system and what the value is set to for the operating system.

Variable	Windows 10	RHEL 8.x
TREK_INCLUDE	Provides a path for all header files needed to integrate the TReK APIs	Provides a path for all header files needed to integrate the TReK APIs
TREK_LIB	Path to the .lib files for integration into C/C++ programs. This is always the 64-bit version of the libraries	Path to the .so files in the TReK install.
TREK_LIB32	Path to the 32-bit version of .lib files for integration into C/C++ programs.	Not available
TREK_LIB64	Path to the 64-bit version of .lib files for integration into C/C++ programs.	Not available
TREK_DLL32	Path to the 32-bit version of .dll files for integration into C/C++ programs.	Not available
TREK_DLL64	Path to the 64-bit version of .dll files for integration into C/C++ programs.	Not available

Library Dependencies
TReK libraries have additional dependencies that are provided as part of the installation. You will need to make sure you have those libraries available for your executable. You can use the environment variables above to find the path for the libraries.

Each of the API help main pages will list the additional libraries that are needed for running.

Error Codes
The error codes described for each library function or method do not include lower level library errors. If you get an error code you cannot find in the documentation for the function, use the search feature of help to find the error code (e.g., 32043).

Examples
Examples are provided for each API and can be found in the example directory in the TReK install.
The examples contain both source and header files. Each example also includes both a Visual Studio solution and Linux makefile for compiling under your preferred operating system.