The purpose of this chapter is to document the API for every internal C function in PLplot (other than language bindings) that is not part of the common API that has already been documented in Chapter 17, The Common API for PLplot or elsewhere. The functions documented here are internal plplot functions. They are not intended for external use and may change between releases.

This chapter is a work that is just starting. There are many C functions in the code base that are not part of the common API, and we haven't even gotten to the point of listing them all. What gets documented here now is whatever C-explicit code we are trying to understand at the time.