Strategy, discovery, metrics, growth, pricing, design, delivery and leadership. Each entry says when it is the right one to pick up.
Lauchengco's product marketing book, part of Cagan's Silicon Valley Product Group series. Defines the role through four fundamentals of ambassador for the customer, storyteller, evangelist, and connector to go to market strategy.
Dunford's ten step process for positioning, treated as a deliberate exercise rather than a byproduct of messaging. The components are competitive alternatives, unique attributes, the value those enable, the customers who care most, and the market category you frame yourself within.
Dunford's follow up applies positioning to the sales conversation. The structure she proposes moves from insight, to the alternative approaches available, to the perfect world criteria those imply, then to the product as the way to meet them, followed by proof and objection handling.