Boondock:

Modality in Rock music:

Rock “Functional Modality,” then, refers to the use of a particular mode as a type of key—in other words, as a pitch collection source for melodic materials and harmonic underpinnings, or chords. Four modes and the scale referred to as the Rhythm and Blues scale function in this fashion in rock music and are developed as such in SECTION TWO. The system may be properly identified as functional modality because not only can any one of the common rock modes (i.e., Dorian, Aeolian, Mixolydian, Ionian, and the R&B scale) be used to generate chords, but it may be established, again through common practice, that certain chords occur at certain times in systematic fashion. Hence, functional modality has pre-tonic and pre-dominant (more properly, pre-pre-tonic) chords. What is more, the various modes often pool their collective chord resources creating bimodal and trimodal conditions in many pieces. Tonal progressions occur, as well, so the theoretical implications in rock music can be very broad (and, therefore, difficult to teach!), although actual conditions are generally not particularly complex in practice. This, then, is the ambitious scope of SECTION TWO, the full extent of which is seldom, if ever, fully understood by the practicing rock musician because specific styles and idioms are more narrow in their focus.

Did a google search, and the first thing I see is a guitar instruction book from my college guitar teacher.