PROC POWER sample size for lower bound of confidence interval

[msecic]

How can I use proc power to calculate the sample size needed for the following

scenario:

2 independent groups 1:2 randomization

2-sided 95% confidence interval lower bound of the mean difference must exceed +2,SD=3.1

  hel

How can I specify the lower bound in the SAS code?

  Thanks!

[Jack2012]

I think you can refer the documentation about this procedure, there is an option to define the ratio.

[msecic]

thank you, Jack2012, but there is no ratio in my example.  I specifically need an example with a confidence interval around a mean difference.