The letter k following the Begin Shape Indicator shows the reader that it is one key on the keyboard F3, rather than Shift F3. (See Section 13.2)
The example should end with the End Shape Indicator. Thank you for pointing out the Caps Release error.
The End Computer Braille Code symbol is the same symbol as is used for the End Shape Indicator. When use in this manner, it would need to listed on the Special Symbols page as the End Shape Indicator.
So, it should have read: [braille]_$k_f3_: