Vulkan render pass interdependencies?

Hi, In Vulkan you have render passes where you specify which attachments to render to and which to read from, and subpasses within the render pass which can depend on each other. If one subpass needs to finish before another can begin you specify that with a subpass dependency. In my engine I don't currently use subpasses as the concept of the "render pass" translates roughly to setting a render target and clearing it followed by a number of draw calls in DirectX, while there isn't really any good way to model subpasses in DX. Because of this, in Vulkan, my frame mostly consists of a number of render passes each with one subpass. My question is, do I have to specify dependencies between the render passes or is that needed only if you have multiple subpasses? In the Vulkan Programming Guide, chapter 13 it says: "In the example renderpass we set up in Chapter 7, we used a single subpass with no dependencies and a single set of outputs.”, which suggests that you only need dependencies between subpasses, not between render passes. However, the (excellent) tutorials at vulkan-tutorial.com have you creating a subpass dependency to "external subpasses" in the chapter on "Rendering and presentation", under "Subpass dependencies": https://vulkan-tutorial.com/Drawing_a_triangle/Drawing/Rendering_and_presentation even if they are using only one render pass with a single subpass. So, in short; If I have render pass A, with a single subpass, rendering to an attachment and render pass B, also with a single subpass, rendering to that same attachment, do I have to specify subpass dependencies between the two subpasses of the render passes, in order to make render pass A finish before B can begin, or are they handled implicitly by the fact that they belong to different render passes? Thanks!