[Tex/LaTex] Command /k unavailable in encoding OT1. – possibly using too many languages in one document

Question

I'm a LaTeX newbie, so please, bear with me (also, I'm not an English native speaker, so I apologise in advance for all my grammar/spelling mistakes).

I'm using LaTeX to format my translation of one chapter of a book (from English to Polish, the subject of the book being a French author reading an ancient Greek one [Racine reading Euripides to be precise] – as you can see there's bound to be many languages there). I've already translated the whole thing and now I'm doing the footnotes and there the problem appeared:

\documentclass{book}
\usepackage[OT4]{polski}
\usepackage[utf8]{inputenc}
\usepackage[french,polutonikogreek,polish]{babel}
\linespread{1.6}
\makeatletter
\def\blfootnote{\xdef\@thefnmark{}\@footnotetext}
\makeatother
\begin{document}
some Polish text - Litwo, ojczyzno moja
\selectlanguage{french}'Vous vous taisez?'
\selectlanguage{polish} coś tam
\selectlanguage{polutonikogreek} sig~a|s t'i pr`os g~hn '>omma s`on bal`wn '>eqeis
\end{document}

I know – this particular code does not produce any problems but my whole text is longer and everything is all right as long as I don't include this line:

\selectlanguage{polutonikogreek} sig~a|s t'i pr`os g~hn '>omma s`on bal`wn '>eqeis

By itself it poses no problems (tried making a document that would have only this one line and it had no problems), also there is no problem when it is included in the main text (I have more greek text there and not a single part of it poses any problem) – but it is in a footnote (one that has the \selectlanguage command 8 times in it) and every time I try to compilate the whole thing with it I get this error: Command /k unavailable in encoding OT1. Also the Polish diacritical signs (ą ę) stop showing up after that. Why is it so and is there any possibility of changing it? There are several more footnotes awaiting translation and almost every single one includes some ancient Greek text together with other languages…

Answer 1

OT stands for "old text encoding"; I believe it's not necessary at all.

\documentclass{book}

\usepackage[T1]{fontenc}

\usepackage{polski}
\usepackage[utf8]{inputenc}
\usepackage[french,polutonikogreek,polish]{babel}

\begin{document}
Litwo, ojczyzno moja ą ę
\foreignlanguage{french}{<<Vous vous taisez?>>}
coś tam
\foreignlanguage{greek}{sig~a|s t'i pr`os g~hn '>omma s`on bal`wn '>eqeis}
\end{document}

Don't use \selectlanguage to switch languages for small excerpts. Better use \foreignlanguage or the environment otherlanguage* for longer passages.