That one just covers the 18F242, 252, 442 and 452 series. Always download the one
specific to the PIC you're using. Things change a good deal from one series to the next.

Also check for & download any errata sheets that might be available. These can save you
a LOT of time. Some series may have a problem not listed in the primary datasheet.

The 18Fxx20 series have 5: http://www.microchip.com/wwwproducts...cName=en010270