Final answer:
In freehand lettering, horizontal guidelines and interlines are used to maintain uniformity in height and slope of the letters.
Step-by-step explanation:
In freehand lettering, a combination of horizontal guidelines and interlines is used to maintain uniformity in height and slope of the letters. The horizontal guidelines serve as a reference for the overall height and placement of the letters, while the interlines help determine the heights of different parts of individual letters.
For example, scribes in medieval times would place each sheet of parchment on a board marked with horizontal guidelines. They would then use interlines to ensure consistency in the height and slope of the letters they were writing.