Thanks for all answers.
On the start this work I was trying to trap compile-time errors but it
seems unavailable. I see, I must to write validation function, something
like Chip's function IsValidProcName() but with my locale chartacters and it
must be more complicated becouse asterix * in Like statement matches
unallowed characters like $, &, ! etc...
Finnaly iteration :( ... or good instructions for users :)

Greetings from Poland
Micha³