Some resource creation may take a long time, especially if compilation or other heavy processing is involved. Some users may think that deployment goes wrong and cancel it. For better user experience, there should be some way to notify user right before resource is created. It's not possible to use "notify" type for conditional message.
Instead of metaparameter, as normal parameter can be added only to "exec", "package" and some other types.
Of course, this is easily achievable with custom providers, but some DSL-level support is desired.