Can you be more specific please?

It only says

The following example prefaces each City in the list with some introductory text, adds some headings and changes the format of the sales field.
[«City» «Representative» «Sales»
]
The fields laid out in this example produce the following output, using the ‘State’ field as the key field:
These are the sales totals for ACT
City Representative Sales
Canberra Yang $2,100.00

Nothing in there to state what is actually outputting the heading in bold.