An instruction manual is an important thing.
H stands for heading
A stands for access
T stands for typography
S stands for space
Heading should be in bold, as there are different features used when writing a document. In the heading area, you should put the major areas to be covered. In important things, they are bolded or italicized. Spacing is also important, as when reading a manual, a user is not wanting everything to be crunched together.