It doesn't get any higher than this. There are two main difficulties here: (1) your hand is over the body on a standard classical guitar, and (2) there are so many ledger lines all the notes start to look alike. To help a bit with the first difficulty, the exercises for position XII don't use the string ⑥ at all, and position XIV even avoids string ⑤ which relieves some of the reaching way across the body.
For help with all the ledger lines, see the DFE section on “Hairy Notes Outside the Staff”; its “double treble staff” trick shows how to visualize an imaginary staff that makes all the high notes look familiar, and its “triad ruler” technique teaches how to leverage knowledge of the diatonic triads to identify higher notes from more familiar lower notes.
Another visualization trick is imagining the high notes two octaves lower, as shown in the fretboard diagrams below. If the high note is on a line, so will the note two octaves lower. And if you mentally remove the lowest two ledger lines from the high note, the other ledger lines will be placed like the staff lines in the ordinary treble clef (same as in the double treble staff trick).
Sometimes music publishers and composers will use an ottava abbreviated 8va to indicate that a passage is to be played an octave higher than it is written, which allows writing in a more familiar lower octave.
“First finger E on first string” (the octave of open first string) locates position XII, while “first finger E on fourth string” locates position XIV. The high notes on string ① are doubled two octaves lower to help with learning their names (two octaves preserves their line/space appearance and allows you to mentally imagine the high note minus its first two ledger lines with the remaining ledger lines representing the lines of the common treble clef).
Scale 18. Minor thirds across position XII.
Scale 19. Minor thirds across position XIV.
The boxes below automatically keep track of which exercises you've seen in this group (you get a gold star for each exercise you visit). And clicking on a box will take you to that exercise (you can see the exercise number by hovering over a box and looking at the url displayed). So all this lets you pick up where you left off in your last session, or go on to some random exercise you haven't seen yet. Courtesy of your browser history.
