I need help with crossover slopes

Some definitions first: 

octave:

a doubling or halving of any frequency results in a progression to the next octave.  A tone at 50 Hz and one at 100 Hz are one octave apart.  Same applies for a tone at 2000 Hz, and the next octave at 4000 Hz.  An octave, using the familiar piano keyboard, is from any note to the next higher of the same note (e.g. C to C...CDEFGABC.  You can see that when you get into the higher Hz numbers you go through a much greater number of Hz to get to the next octave.

decibels (db):

the next change in loudness that a human can perceive.  (Some of us older guys who have started the onset of hearing loss have a harder time perceiving those slight differences, BTW.)  3 db is generally considered a change in loudness that is noticeable, like if someone asks you to turn the radio up, you turn it up enough to make a difference....that's about 3 db.

db/octave:

how many decibels per octave? stated in decibels per octave.  Or, what is the loudness at the next octave compared to what it is at this one?

slope:

the change in loudness from one octave to the next, shown as db/octave.  Crossovers, when simply built, are called 1st order.  They consist of only a capacitor or only a coil, depending on if they are working as a lowpass or a highpass.  The change in loudness for these is 6 db/octave.  2nd order crossover slope is 12 db/octave...a more complicated crossover using multiple components.  As the crossovers become even more complicated, steeper slopes of 18, and 24 db are made.

Ideally, for setting crossovers, you take the time to experiment.  If you have the choice to crossover mids and highs with varying slopes, start with the steepest ones available.  Adjust to a frequency that blends the two speakers' sound.  As you listen to nuances in the music, you can change the slope until you finally arrive at a crossover setting where the music sounds natural and good to you.  Mids-to-tweeter slopes are often steeper than sub-to-mid slopes for best natural transitions.  And if you're adjusting a crossover with a set type of slope, such as 12 db/octave...you only adjust the frequency to arrive at the best sounding transition.

I think he means what KIND of crossover?  In your HU?  Built into a processor or an amp?  External stand alone?  Make/model?