Third rotational angle in equatorial coordinates
This angle is dependent on the specific positioning of the eyepiece on your telescope. For models on which the tube can be rotated or custom-positioned, this means there are even more possibility—technically, an infinity.
However, no matter which telescope you use, the angle of rotation of the field of view will not change as objects move across the sky due to the Earth’s rotation if you are using an equatorial mount. Of course, using an altazimuth mount would make this angle change with time.
Usually, angles increase eastwards at the eyepiece. See for example https://en.wikipedia.org/wiki/Position_angle
Clear skies!