Rostering at KAL for the OFF days is on the "normal" program 9 OFF days/month and in addition you have 24 leave days/year available. So average 11/month. You submit your OFF days online and it alwasęs works so far (for me 100% since 7 years) as long as you stick to the rules (i.e. min 9 days, max 16 days/month, back to back with prior approval....) And for your OFF days you deadhead to your home and back (NOT included in the OFF days, travel days (max 3/month) are in addition).
The "reverse pattern" (wording from China??) here is called "Option". On that you operate on duty home and back to ICN, and on average you will get 2 blocks of 5-7 days OFF/month. But you can NOT choose when! Option program here is quartely (so can try for 3 month and if it is not suitable go back to normal program...)
All pretty easy and straight forward..