You'll note that all functions begin with the letters Speech. To avoid conflicts with Rexx Speech function names, do not name any of the functions in your REXX script starting with those 6 letters (neither upper nor lower case).
If any of the functions are called before a speech engine is opened, then they usually perform no work and raise a REXX SYNTAX condition. Failure to supply required arguments (or supplying invalid arguments) also raises a SYNTAX condition. Other errors do not raise a SYNTAX condition, but instead return an appropriate error indication to your script. For example, if SpeechSpeak() fails to speak the text, then it returns an error message. It's up to your script to check returned values for any errors in performing an operation. Always do error checking upon the return from a Rexx Speech function where appropriate.
The sections of this book leading up to the list of functions describe how to do various tasks with the Rexx Speech functions. So, they are overviews (ie, tutorials) of how to use Rexx Speech in various ways, whereas the list of functions are more of a reference complete with incidental notes/details.