Examples of (b) would be common actions like "strip ads for user X but only when she is surfing with her mobile phone browser Y", or "do spam filtering for user X unless the message is from Y"; where X and Y are parameters. I would imagine vendors and user groups might want to create collections of such common parameterized actions. P would need to have something like user-defined functions to support this. [...] The advantage is that OPES processor will only need to support one, albeit more complex, language instead of two or three. It is not clear to me whether we can capture both (a) and (b) without significantly increasing P implementation complexity.