What does this resistor symbol mean?
I came across resistors with odd symbols (see page 18). They are trapped between two parallel lines (for example, 3297).




(Crop from the original schematic, showing the unknown resistor symbol.)



Answer: That is one of the (many) symbols used for a fusible resistor. Here is an extract from page 177 in the book: Electronics for Service Engineers by Joe Cieszynski and David Fox (Google Books link to page 177) showing that symbol, which I've marked in red below: