What is meant by mindful in-breathing, mindful out-breathing, and abiding with mindfulness?

Regarding the dharma currently being contemplated and cultivated, being able to focus with single-minded attention, without distracting thoughts, is right mindfulness. Right mindfulness is the thought that should be maintained in the present moment—a thought consistent with the object of contemplation at present, and also a thought of direct perception. For example, when contemplating the in-breath, the entirety of one's attention rests on the in-breath: from the moment the breath enters through the nostrils until it travels down to the dantian, the whole process is contemplated with focused, single-minded attention—purely objective and simple observation, without mental activities such as thinking, analyzing, reasoning, or imagining. There is only simple knowing; other dharmas are not attended to, not engaged with. Nor does one contemplate how the body's sensations feel—the mind does not dwell on sensations, only on the in-breath. The same applies to the out-breath, and the same throughout both the in-breath and out-breath. The practice of any other dharma should be like this as well. This is what is right—this is the correct and proper method of diligent practice. Only by unifying the mind, equally cultivating Samādhi and Prajñā, without leaning to either side, can one enter the Path.