i don't get into all that technical stuff. i just read and re-read cervante's plain english decription of how to create a stable strain and use that definition.
cross your parents creating a hybrid. back cross those creating a BX (that's the term i use) then split your offspring into two separate lines with 2 males and two females and select for desired traits in as wide a field as possible, preferably at least 100, and then repeat the process for something like 3-4 generations until you've created 2 lines that share the traits you were breeding for and then you can chose a male from one line and your female from the other for a true breeding strain.
all of that f2 diploid, triploid, polyhybrid 4 square recessive mumbo jumbo goes in one ear and out the other with me. i just know the basics and am happy enough with that knowledge. even if i wanted to make a true breeding strain, i don't have the space or citizenship for that matter to do it. i just pick my favorite strains from everything i've tried as my parents and let my chosen males, so far just selected for shorter stature with C99 and faster flowering with my C99xA11 male last time. i'm just having fun making beans, nothing technical, and no more than a a couple females of any strain to select from as breeders.
i appreciate quality, but not as fanatically as many here that turn their nose up at even growing a strain without testing at least 50 females for a keeper. most of the stuff i've grown has made me happy as i've bought strains that get you high almost exclusively and THAT is all i care about. any strain that doesn't make me a stoned drooling fidiot works for me. i do all of my selecting at the strain level.
the only serious pheno variation i've seen so far was in my masterkush autos where i had 3 distinct phenoes, a big blonde amazon, 2 dark green shorties and one outstanding shortie that had dark, but deep crimson seed pods that i selected as a color breeder. the only other grow i've done where i had multiples of a strain was my 1st C99 grow where a couple were tall and 3 of them were shorter, but they smoked about the same.
you'd learn more about advanced breeding by reading than talking to me. i've pretty much shared all i know already... just the basics.