$#HyperText

HyperText is a form of electronic book in which the reader, instead of following a preset path
 from beginning to end, is able to move around by means of selecting key words or phrases
 within the 'Book' that perform a jump to a new location within the 'Book'.

$#Topic

The term Topic in this context refers to a HyperText page of information. Each Topic has a
label by which it is accessed, and optionally a Title which can be used when performing a
search.