The bundle provides basic facilities for LuaTeX macro
programmers, mostly resource allocation and convenience
packages. Provided are: - luatexbase-attr: attribute
allocation; - luatexbase-cctb: catcode table allocation; -
luatexbase-compat: compatibility helpers; - luatexbase-loader:
Lua module loading; - luatexbase-modutils: Lua module
declaration; - luatexbase-mcb: callbacks extension; and -
luatexbase-regs: allocation of registers and the like. In
addition, the (unadorned) luatexbase package loads all the
above in one fell swoop.

Homepage:
https://www.tug.org/texlive/
