The TikZ and PGF Packages
Manual for version 3.1.10
Part X The System Layer
by Till Tantau
This part describes the low-level interface of
pgf, called the system layer.
This interface provides a complete abstraction of the internals of
the underlying drivers.
Unless you intend to port pgf to another
driver or unless you intend to write your own optimized frontend,
you need not read this part.
In the following it is assumed that you are familiar with the basic
workings of the graphics package and
that you know what
TeX-drivers are and how they work.