"The characters table is a list of character hashes indexed by an integer number": The sentence says that the table is a list. According to 'Programming in Lua' that indeed is the case. But the term 'list' conveys that the order of the items is something that matters, which (most probably) is not the case here. As far as I see, the intent of the table is to just map character codes to character information. Using the term 'list' in that context is a bit misleading. "and tell the engine that œ counts as one character": I think it should be "two characters". "In figure ?? and 7.7 we show what happens with three samples" "(the ones resulting from an \exhyphenchar": Missing closing parentheses. "the case relate codes": "relate" instead of "related". "This word separation is worth mentioning because": Should be "separation of stages" or just "separation" instead of "word separation". Maybe "work separation" was intended. In the table at the top of page 80, the "sub 1" probably should go directly below "POST", and the "sub 2" directly below "REPLACE". Now they occur aligned to the numbering of the terminal nodes of the structure presented in the table. "it does not expect there to be discretionaries inside of discretionaries": As far as I understood the previous text, what is really meant here is "it does expect there not to be discretionaries inside of discretionaries". The Lua(Meta)TeX manuals talk about ghost nodes. I did not find any information on what that is. Up to now, for all other stuff encountered in the LuaMetaTeX manual that I did not know and wanted to have a rough idea of what it is about, I found the relevant information either in the LuaMetaTeX manual itself, in TeX by Topic, or in the ε-TeX manual. I.e. I found it using the LuaMetaTeX manual itself, or the manuals that were referenced at the beginning of chapter 1 of the LuaMetaTeX manual as important additional material. The Lua(Meta)TeX manual mentiones that \leftghost and \rightghost come from Aleph. I searched the web quite a bit about Omega and Aleph on that issue, and tried other things, but found nothing of relevance. There is a manual for Omega, but, after conversion from ps to pdf, and opening the pdf with Evince, the search function did not find the phrase 'ghost' in it, either.