A big improvement of dsPIC33e series micro-controller from its predecessors is the re-mappable peripheral IO. This allows great flexibility for circuit board design, but also requires slightly more efforts to use it… continue onyu.xueming.org
Updates: my blog has moved! Check out yu.xueming.
Xueming Yu 
As for the “Why are outputs configured the other way round compared to inputs”, it’s because everything can have multiple effects, but only one cause.
Take any input. You can assign this input to as many peripherals as you want. But every peripheral can only be fed by one input signal.
Outputs have to be different because you can’t have several peripherals fight each other who’s to set or clear the pin. But you can have several pins all reflect the result of the same peripheral (e.g. to get more milliamperes into an LED without external circuitry at the cost of more pins).
Hi,
The article helped me to understand the concept of peripheral multiplexing , thanks for sharing.
Could you explain the same concept in context of dsPIC33e QEI configuring for Position counter as well as input capture. My application is to find low speed calculation using a 1000 ppr encoder.
Thanks
Saneesh