The old school method was to use hard board, staple, patch and sand it, then install whatever the resilient product was. Well, the evolution has caught up. Underlayments are just not that generic anymore. It seems the resilient manufacturers have stepped back from underlayment and placed the decision on product usage upon whomever is supplying and installing it. There is a large choice of products, and the range is ever increasing with imported woods. In fact, it is easier for the flooring manufacturer to provide information on what not to use. Then again, those recommendations will vary.
There are conflicting installation recommendations between the manufacturers on issues such as whether to: butt the panels, or leave a slight gap; patch the joints, or don't; sand before patching the joints, or sand after patching the joints. While some panels are pre-printed with a stapling grid, other manufacturers recommend a random stapling that does not leave a pattern that could telegraph through. The objective is the same for everyone: provide a clean, smooth surface that an adhesive can bond to.