The package will directly insert nonbreakable spaces (in Czech, vlna or vlnka), after nonsyllabic prepositions and single letter conjuctions, while the document is being typeset. (The macros recognised maths and verbatim by TeX means.)

(Inserting nonbreakable spaces by a preprocessor will probably never be fully reliable, because user defined macros and environments cannot reliably be recognised.)

The package works both with (Plain) XeTeX and with XeLaTeX.

See also encxvlna.

The author is Zdeněk Wagner.