The problem of finite word length implementation is discussed in this paper. Alternatively to the rhoDFIIt recently proposed by G. Li et al., and leaning on the specialized implicit form for a unified analysis, a new effective and sparse structure, named rho-modal realization, is developed. This realization meets simultaneously accuracy (low sensitivity, round-off noise gain and overflow risk), few and flexible computational efforts with a good readability (owing to sparsity), and simplicity (no tricky optimization is involved) as well. Two numerical examples are presented to confirm the theoretical results and illustrate the rho-modal realization interest.