Although Z notation (just like the APL language, long before it) uses many non-ASCII symbols, the specification includes suggestions for rendering the Z notation symbols in ASCII and in LaTeX. There are also Unicode encodings for all standard Z symbols.
ISO completed a Z standardization effort in 2002. This standard and a technical corrigendum are available from ISO free:
the standard is publicly available from the ISO ITTF site free of charge and, separately, available for purchase from the ISO site;
the technical corrigendum is available from the ISO site free of charge.
^Meyer, Bertrand; Baudoin, Claude (1980), Méthodes de programmation (in French), Eyrolles
^Abrial, Jean-Raymond; Schuman, Stephen A; Meyer, Bertrand (1980), "A Specification Language", in Macnaghten, A. M.; McKeag, R. M. (eds.), On the Construction of Programs, Cambridge University Press, ISBN0-521-23090-X (describes early version of the language).