Anima Astrologiae or A Guide for Astrologers by William Lilly 1676

The 59th is to Consider, Whether the significator be behind the cusp of an angle 15 degrees and no more; for he shall be said to be in an Angle as well as he that is exactly there, as ‘Zael’ affirms; whence he said before that it was not in an Angle, nor had any strength there beyond the 1 5th degree after the cusp of the Angle: For example, the Ascendant is 4 degrees of Taurus, and the end thereof was behind the Angle, whatever planet is posited from the 4th to the 19th degree thereof is in the angle, but what is beyond that is not; but Ptolemy seems to imitate, though he says not expressly, “that every planet who shall be 5 degrees before, or 25 degrees after the cusp, is in the Angle.” Now ‘Zael’ would clear the doubt, lest that great distance of the planet from the Angle should hinder the business.

60.Whether the Significator be in a Fixed, Moveable, or Common Sign