BNF Grammar Derivation

I want to开发者_运维问答 apply rules of BNF Grammar to produce derivation for : a_Num

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Your question is a bit vague. But below is a BNF (ish) grammar for an integer number.

nz_digit   = '1' | ... | '9';
digit      = '0' | nz_digit;
digitseq   = digit | digitseq, digit;

num        =  '0' | nz_digit, digitseq;