CAN control register

[IRT]

below is from the data sheet of the PIC18F4680. this bit is in the register:
CIOCON: CAN I/O CONTROL REGISTER

bit 5 ENDRHI: Enable Drive High bit(1)
1 = CANTX pin will drive VDD when recessive
0 = CANTX pin will be tri-state when recessive
Note 1: Always set this bit when using differential bus to avoid signal crosstalk in CANTX
from other nearby pins.
I wonder if anyone could provide a better explanation of what note 1 means.
Thanks

[PCM programmer]

A typical CAN bus driver such as the MCP2551 has single-ended input
and output pins on the PIC side. The CAN bus side is differential.
The ENDRHI pin controls whether or not the CANTX pin on the PIC
is either driven high or is pulled up by an external pull-up resistor.
Not all CAN bus driver chips have a built-in pull-up on their TX input.
In the case where your CAN bus driver chip doesn't have a built-in
pull-up, and you don't want to add an external pull-up to your board,
you must set ENDRHI so it drives CANTX high, instead of tri-stating it.
See this thread, in which we discover this:
http://www.ccsinfo.com/forum/viewtopic.php?t=23825